Not their 60s, not their 40s, not their 80s, not their 20s: Their 50s.
Julia Louis-Dreyfus, age 54
Susanna Hoffs, age 56
Sheryl Crow, age 53
I’m partial to the ladies, but feel free to add a fella or two.
Robert Downey Jr., squeaking into the club at 50
Hugh Laurie, 55
Peter Capaldi, 57 (okay, he’s kind of weird-looking, but I like weird-looking guys with charisma)
Ming-Na Wen, age 52.
Please don’t forget Diane Lane. 
Well, you took my example right off the bat. She is gorgeous.
She’s hotter now in her mid-50s than she was at the start of Seinfeld when she was in her late 20s. IMO.
Lisa Kudrow and Courtney Cox are both in their 50s now (4 or 5 more years to go for Jennifer Aniston.
They are both holding up pretty well but not as well as Diane Lane and Famke Janssen IMHO.
Heather Locklear is still looking very sexy too; but since she hasn’t been in anything that I’m aware of lately; it’s hard to say.
Helen Hunt was on Fallon the other day and I’d definitely say she’s still very sexy.
However If this turns into a poll; I already know I’m voting for Diane Lane or Julia Louis-Dreyfus as my first choice.
Catherine Keener (56)
http://www1.pictures.zimbio.com/gi/Catherine+Keener+Elephant+Song+Premiere+2014+nSpciarVzD1l.jpg
Wesley Snipes, 52!
(I can’t believe Alan Rickman is 69. And Denzel 60! How old does that make me?!)
I thought she was hot back then too. They just saddled her with a terrible hairdo. I don’t know if that was stylish back then, or if it was just supposed to make her character look like a doofus. Anyway, I remember taking some grief from my college buddies in the 90s when I said Julia Louis Dreyfus was sexier than some supermodel (Cindy Crawford maybe). They thought I was a freak. How wrong they were! And she’s still sexier than Cindy Crawford (who I learn is only 49 and thus not qualified for this thread anyway).
Sandra Bullock.
Next question?
You nailed it right out of the chute.
Brad Pitt, Johnny Depp, Tom Cruise, George Clooney, Robert Downey jr, etc are all in their 50s now. They seem like they have held up well.
Jodie Foster. Also partial to the ladies.
Which in Downey and Depp’s cases (i.e. lots of substance use) is particularly impressive.
A seconding of Julianne Moore for the ladies.
I’ve never thought Dylan McDermott was a great actor but he has a great bod in his 50s.
Have you forgotten her 1995 Emmys dress? And then there was another one later on that was fairly notable, but I can’t find a link.