Theme: All is calm, all is bright. The circled letters, in order, spell the word NIGHT; and each letter is silent in both of the down and across words in which it appears. If you didn't get the circles, I don't know how you'd deal with it.
Silent N:
20 A. Spreadsheet figure : COLUMN TOTAL. Typical spreadsheet math.
6 D. "Ave Maria," e.g. : HYMN. A religious song.
Silent I:
25 A. Take by force : SEIZE. Suddenly and Forcible take hold of something.
11 D. Stereo components : RECEIVERS. They convert broadcast signals into visible or audible form.
Silent G:
33 A. Prosecutors, at times : ARRAIGNERS. They bring someone [a perp, perhaps] before the court to answer a criminal charge.
10 D. Station identification letters : CALL SIGN. Unique alphanumeric designations of transmitting stations. They are used in commercial radio, amateur radio, transportation and the military.
Silent H:
37 A. Cheering word : RAH. Perhaps shortened from hooray/hoorah, 'cuz we're just that lazy.
32 D. Present day? : CHRISTMAS. The day when Christians commemorate the birth of Jesus. The Magi brought him gifts, and so we give each other gifts. The "present" day can be either today, Christmas Eve, as we celebrate with the Bumpa clan, or Christmas day, as we celebrate with my mom and sister.
Silent T:
54. Clever remark : MOT. Actually BON MOT, the French designation for a witticism.
32 D. Present day? : CHRISTMAS. Making a second appearance, 'cuz - why not? It's that kind of day.
And the unifier:
55 A. Classic 6-Down suggested by this puzzle's circles : SILENT NIGHT.
One might quibble, perhaps, with the degree of silence some of these letters actually present. But let's just go with it. Who but hard/soft G Don Gaglairdo could so exploit the vagaries of the English language, to bring us such a brilliant and timely construction? This is his present day present to all of us.
Hi gang, JazzBumpa here, happy to present you with Don's holiday greeting, and a whole bunch of music.
Across
1. Flexible lunch hour : ONE-ISH. More or less 1 O'clock, kinda, sorta.
7. PC speed unit : M-SEC. Milisecond. 1/1000 second.
11. D.C. United's __ Stadium : RFK. Named for former attorney General Robert F. Kennedy.
14. Marvel Entertainment parent company : DISNEY. Entertainment empire.
15. Cinders of old comics : ELLA. Here is her introductory panel from 1925. You might need to blow it up to make it readable. Read more here. Turn her name around to suss the inspiration.
16. Reef dweller : EEL. Any of 800 species of elongated, mostly predatory fish.
17. Needing to be bailed out, maybe : IN A JAM. Some sort of tough spot, possibly jail.
18. "Double, double, __ and trouble": "Macbeth" : TOIL. "Fire burn and cauldron bubble." Witches' incantation.
19. DCIV ÷ IV : CLI. Roman numerals. 604/4 = 151. How did the Romans ever master division?
22. Individual : SSN :: corp. : __ : E I N. Employer Identification Number.
23. Hospital fluids : SERA. Fluids separated from clotted blood, unlike plasma, which comes from unclotted blood. Did anyone besides Marti know that?
24. "Impressive!" : OOH! Like this puzzle.
27. Happen afterward : ENSUE. Does this imply cause and effect?
29. Capital on the Dnieper River : KIEV. Capital and largest city of Ukraine. I've heard they have a Great Gate there.
30. Tot's recitation : ABC'S. 1-2-3's, too.
38. Nod from the maestro : CUE. Indication you can start playing now. And much appreciated after 179 bars of rest.
39. Short or gross measure : TON. A short TON is the 2000 lb. measure we are used to in the U.S. A gross TON is the same as a long TON, 2249 lbs.
40. See 59-Across : RAP.
59. With 40-Across, trumped-up charge : BUM. A BUM RAP is a false charge resulting in a miscarriage of justice.
41. Ones making the rounds? : BAR TENDERS. Mixologists preparing rounds of drinks. Clever!
44. "The Thin Man" pooch : ASTA. Movie dog.
45. Dot on un mapa : ISLA. A Spanish island.
46. Capital of Senegal : DAKAR. Un Mapa.
48. Debate subject : ISSUE. Topic under discussion.
50. Bon __: Comet rival : AMI. Scouring powders.
51. Sports fan's factoid : STATistic.
60. Holiday purchase : TREE. Yo, Tannenbaum!
61. Remove all doubt : BE SURE.
62. A, in Oaxaca : UNA. Spanish indefinite article.
63. Gremlins and Matadors : AMC'S. American Motors Corp. automobileS from the past.
64. Lustrous fabric : SATEEN. A fabric made with satin weave structure using spun yarn instead of filament.
65. Mag staff : EDS. Abbreviated editors.
66. "... be good for goodness' __!" : SAKE. Pam provides the details, with a little help from her friends.
67. Determined ahead of time : PRESET.
Down
1. Like many Keats poems : ODIC. He wrote the most ODIC of odes. Fortunately, most of them are neither odious nor oddities.
2. Bogotá boys : NINOS. Those boys speak Spanish
3. Online transaction : E-SALE. A unit of E-Tail.
4. Harms : INJURES.
5. Crew member : SEAMAN. In the Navy
7. Copycat : ME-TOOER. Conveniently constructed, but a welcome reprieve from the ubiquitous APER.
8. A deadly sin : SLOTH. For those too lazy to indulge in gluttony and lust.
9. Oscar-winning director Kazan : ELIA. Gentleman's Agreement, On the Waterfront.
12. "__ Navidad": Feliciano song : FELIZ. Merry Christmas in Spanish.
13. Kevin of "Dave" : KLINE.
21. Took the show on the road : TOURED.
26. Poetic time of day : E'EN. Even I know this is evening, thus eventually evening me with all of you.
28. Post-workout destination : SAUNA. Steam bath.
29. Mall stand : KIOSK.
30. Wall St. hedger : ARB. Slothful way of indicating an arbitrageur, one who attempts to profit from price inefficiencies in the market by making simultaneous trades that offset each other and capturing risk-free profits.
31. Cote cry : BAA.
34. Transport in an Ellington classic : A-TRAIN. The quickest way to Sugar Hill in Harlem.
35. Informant : RAT.
36. Hotel amenity : SPA.
38. Instruments that sound similar to glockenspiels : CELESTAS. But with a softer and more subtle timbre. It was invented by Auguste Mustel in Paris in 1886. Tchaikovsky was the first major composer to use it in an orchestral setting, first in The Voyadova, then - most famously - in the Sugar Plum Fairie's dance in The Nutcracker. You can hear one starting at about 6:40 of this video.
42. The Tigers of the Ohio Valley Conf. : TSU. Tennessee State University.
43. Attorney general under Ronald Reagan : ED MEESE. Not related to Mickey, as far as I know,
44. Entertainer : ARTISTE.
47. Equally hot or cold? : AS NEAR. I don't quite get this one.
48. Inspire deeply (with) : IMBUE. As with a particular feeling or quality.
49. In good shape : SOUND. Hale and hardy.
50. Smart guy? : ALECK. My comrade at arms.
52. Fits of fever : AGUES. Fever and shivering.
53. French hens count : THREE. You know the song.
56. "__ la Douce" : IRMA. The story of a Parisienne prostitute.
57. Recipe meas. : TBSP. TaBle SPoon. Alternatively, to make out with the cook.
58. Hiker's shelter : TENT. Portable lodging.
Beautiful start to the holiday with this brilliant puzzle from Don G. Hope you all enjoyed it, and are happy and healthy and ready to dive into the new year.
Cool Regards and Feliz Navidad, Happy Kwanzaa, Fabulous Festivus, a not very Saturnine Saturnalia, or whichever near-solstice celebration you prefer.
