I love, love, love showtunes! I suppose my top five with suffice for now (I'll post my version of the classics), but I'll likely post more videos as I remember all of my favorites.
When I think "classy" I think Fred Astaire. And this bit will forever epitomize for me his everlasting awesomeness.
This song sticks with you for days, Ann-Margret is one of the sexiest women I have ever seen. She convinces me that women are people.
Honestly I could post everything from Annie but I went with this one purely because of Tim Curry.
As one youtuber so aptly put it: "Only Tim Curry can sexually open an envelope."
Oh god. Oh god oh god oh god oh god. I love this production so much, this song makes my bones dance.
OBVIOUSLY I'm going to post Barbra Streisand. This song is what I think of when I think of showtunes.
EDIT:
Yes, RHPS absolutely counts.