This is a really great grid layout, with a ton of excellent entries. I broke in with RIBISI, which helped to get OMNI (nice "lead-in" to science), and GASTON, and I was off. The long answers in the top section are all excellent, particularly WORLDBEATERS and GENIEOFTHELAMP. When I had filled in the NE corner, ____MASH was not hard to figure out as an entree to the middle section.
My error came by putting Rca in for RKO. Really, that's just silliness right there. The problem came because when I finished the puzzle, I had corrected the K but not the O. And ITSAMEMARIa somehow seemed okay, because maybe Mario said it to his female friend? No? Nobody's going to buy that?
Meanwhile, 20D: The guy of your dreams? (SANDMAN) and 22D: Workers making preparations to retire? (PITCREW) are both very nice QMCs. The latter reminds me also of that great clue from a couple of days ago.
The lower half is pretty fine work as well. I particularly enjoyed DEMOCRATICALLY, which is the way I'd like our country to operate more of the time, and 48A: Short cut that bypasses a canal? (CESAREANSECTION) is great (although people who undergo said operation might quibble with the idea that the cut made by the scalpel is all that short).
How about that diagonal row of Bs in the SE corner? BERTHA BASAL BENE BID. BEIT BECCA BARTAB (very nice) BESTILL.
I very much enjoyed this puzzle. But I've got to cut these FWOEs out for the ACPT!