Lets start with the unifier -- 24 D. Top-of-the-line, and what each of the four longest puzzle answers begins with? : HIGH END. Indicating merchandise with a large price tag, presumably justified by comparable quality or some other mark of desirability. Let's see how it fits with the theme entries
A HIGH ROLLER is a big spender or one who places large bets.
9. Act too quickly : JUMP THE GUN. An expression derived from racing events, where the start of the race is announced with a piston shot. One who starts too soon acts too quickly and can be disqualified.
The HIGH JUMP is an athletic event in which competitors jump over a horizontal bar.
To be on one's HIGH HORSE is to act in an arrogant and disdainful manner.
31. Cartoon bird that first appeared in "Fast and Furry-ous" : ROAD RUNNER. Here's a clip from the 1949 cartoon.
To take the HIGH ROAD is to behave in a morally superior manner, as for example, to avoid being drawn into acting negatively. Probably not compatible with the previous theme entry.
Hi gang - JazzBumpa here to explore today's offering. Janice Luttrell has given us a rather unusual grid with a couple horizontal 9-stacks. But the theme answers are all vertical 10's and 11's. This inevitably leads to a large number  of three-letter fill, due to grid constraints. But the average word length is 4.92, solidly in the Wednesday pocket. Why arrange it this way? Each theme word that combines with the unifier is at the HIGH END of its fill. So the theme not only works on its own; it also illustrates itself graphically. Most elegant!
Let's see what other goodies we can uncover.
1. Dropped the ball : ERRED. Misplaying the ball is one way to make an ERROR in baseball. Throwing inaccurately is another.
6. Pantry pest : ANT. They bug me.
9. Puts in a cooler : JAILS. American slang
14. Successor of Pope John X : LEO VI. His term ran from ca. June, 928 until his death in ca. February 929.
15. Like many indie films : LOW BUDGET.
17. "You Be __": 1986 Run-D.M.C. hit : ILLIN'. Whateva'.
18. Dr. Brown's classic drink : CREAM SODA. Rated good, not great.
19. Pasadena institute : CAL TECH. The California Istitute of Technology, a private university specializing in science and engineering.
21. Mysterious power : ESP. Extra-Sensory Perception. The ability - if you believe that sort of thing - to acquire information without using the known physical senses, including such psychic phenomena as telepathy, clairvoyance and precognition.
22. Slush Puppie maker : ICEE. Producer of frozen beverages under the ICEE and Slush Puppie brand names.
23. Little snicker : HEH. Not to be confused with a small candy bar.
25. Cries out for calamine : ITCHES. As from a bug bite or other skin irritation.
30. Three times, in an Rx : TER.
31. Notes after do : RE-MI. In the English language version of solmization, these are among certain syllables assignment to musical scale steps.
32. Prefix for "time" : CHRONO -. From the Greek god CHRONOS, a personification of time.
33. __-wop music : DOO. A pop music vocal style originating in the U.S. during the 50's characterized by close harmonies and often using nonsense syllables in the main line or the accompaniment.
35. Starting device: Abbr. : IGN. Ignition, for internal combustion engine powered vehicles.
37. Belgian banknotes : EUROS. All over Europe.
38. Speedmaster watchmaker : OMEGA. This is a line of CHRONOGRAPH [time display plus stop watch] wrist watches. They have been worn by U. S. astronauts during NASA's Gemini 4 and Apollo 11 missions. It is the only watch qualified for extra-vehicular activity.
40. __ Na Na : SHA. A retro doo-wap singing group, and also their TV show of the same name, that ran from 1977 to '81. Their name is derived from this song, originally recorded by the Silhouettes in 1957.
Are you picking up some mini-themes?
41. Gypsum painting surface : GESSO. A mixture of pigment, gypsum and/or chalk with a binder used a primer to prepare a wood of canvas painting surface.
42. Whittled : PARED. Trimmed down, either literally or figuratively.
43. President pro __ : TEM. The second highest ranking official in the U. S. Senate, typically the most senior member of the majority party. According to the Constitution, the Vice president of the U. S. is the President of the Senate. Theoretically, the President Pro Tem acts in his absence. In practice, though, neither person actually presides over the Senate. This responsibility is rotated among junior senators of the majority party, to give them procedural experience - or, more likely, because the senior members foist it upon them..
44. Salt Lake City collegian : UTE. One who matriculates at the University of Utah.
45. Remains in the fire? : EMBERS. Last glowing bits that will soon be ashes. Nice play on "remains."
47. Wolfgang's veto : NEIN. No in Germany - or Austria.
49. Baseball uniform part : CAP.
52. Doesn't go for the green, in golf : LAYS UP. Deliberately shoots short of the green, or to avoid a hazard, as a safety play, hoping to have a better opportunity on the next shot.
53. U.K. military award : DSO. Distinguished Service Order, a military decoration awarded to officers for meritorious service in wartime.
54. Buckwheat noodle : SOBA. From the Japanese word for buckwheat.
55. Earn after taxes : NET. Take home pay.
57. "I Know Why the Caged Bird Sings" autobiographer Maya : ANGELOU. [1928-1914] American poet, playwright and civil rights activist.
59. Writer of medical thrillers : ROBIN COOK. [b 1940] His novels, many of which have become best sellers, sometimes explore controversial topics.
64. Book with interstates : ATLAS. Book of maps
65. Like California, to a Hawaiian : STATESIDE. Referring to the continental U. S. from outside the country, or from the detached States.
66. Gape : STARE. Specifically to do so open-mouthed, as from amazement. Vide supra.
67. One in a cast : ACTOR. It's traditional to tell an actor "break a leg" before the performance. If taken literally, could lead to a double meaning.
68. WKRP's Nessman : LES. portrayed by actor Richard Sanders.
69. Pasture groups : HERDS. Of cattle, presumably.
1. Draw out : ELICIT. To cause a reaction by one's own action.
2. Tighten, as sneakers : RELACE. And retie.
4. Party-planning site : EVITE. Check it out.
5. Use the good china, say : DINE. As opposed to chowing down, which could just as easily involve paper plates and plasticware, or merely hovering over the sink.
6. Lead-into-gold practitioner : ALCHEMIST. Using the BASIC principle of purification to achieve gnossis [mystical enlightenment,] an ALCHEMIST strove to transmute base metals into noble metals, create panaceas, and achieve immortality, Not sure any was ever successful.
7. Negative connector : NOR. Neither's companion.
8. Overly cute, to a Brit : TWEE. What would we say, STATESIDE? Cutesy?
10. Source of much website revenue : ADS. Annoyances, to my way of thinking.
11. "Need __ on?" : I GO. Yes - tell me more!
12. Had no one to catch : LED. As in a race of some sort.
13. BART stop, e.g. : STAtion.
16. Rudimentary : BASIC. Or fundamental.
20. Revolutionary Guevara : CHE. [1928 - 1967] An Argentine Marxist revolutionary, diplomat and military theorist who became a major figure in the Cuban revolution.
26. Dressing holder : CRUET. A flat-bottomed vessel with a narrow neck, a stopper, and possibly an integral spout.
28. Hall of Famer Slaughter : ENOS. [1916-2002] His career spanned 1938-1959, interrupted by military service from 1943-5. He was a 10-time all star and played in the World Series 5 times.
29. Only fair : SOSO. Mediocre.
34. Fancy moldings : OGEES. S-shaped double curves.
36. Some first-born children : NAMESAKES. They are named after ancestors or older relatives.
38. Volkswagen rival : OPEL. A German auto company that is a subsidiary of GM, headquartered in Rüsselsheim.
39. Doll's cry : MAMA.
46. Short job details? : SPECS. Here, it's the designation of the job details that is short, not the job itself.
48. Electrified particle : ION. Hydrogen atom: "I seem to have lost my electron." Chemist: "Are you sure?" Hydrogen atom: "I'm positive."
50. On the train : ABOARD. On board, probably influenced by Old French.
51. Stops to think, say : PAUSES. Causes a slight break in the action.
54. Luigi's lucky number? : SETTE. Seven in Italian.
56. Work very hard : TOIL.
58. Deep cut : GASH.
59. Zimbabwe neighbor: Abbr. : Republic of South Africa.
60. Non-Rx : Over The Counter.
61. Night flier : BAT. Effective mosquito controller, too.
62. Olympics skater Midori : ITO. The first female to complete the triple axel in competition in 1988. It became her signature move.
63. Neruda wrote one to salt : ODE. . . . sprinkling vital light upon our food . . .
63. Neruda wrote one to salt : ODE. . . . sprinkling vital light upon our food . . .