I've seen a zillion musicals over the years - one of the benefits of living close to NYC. The first one I saw was Into The Woods, with Phylicia Rashad as the witch. I don't think I could even remember all the ones I've seen:
Les Mis - seen it three times, unbelievable
Phantom - sorry to those who love it, but IMHO this is probably one of the worst I've ever seen. I even saw it a second time just to make sure I wasn't imagining it.
Cats - Ehh, I probably should have seen this at 5 instead of 18...
Sunset Boulevard - Almost as bad as Phantom, even with Glenn Close
Guys and Dolls - with Nathan Lane - UNBELIEVABLE
Rent - good music, but overrated
Damn Yankees - lots of fun
Chicago - awesome
Cabaret - unfortunately I saw this with John Stamos, who was horrible
The Fully Monty - Fantastic - saw it twice!
Joseph and The Amazing Technicolor Dreamcoat - I saw Donny Osmond in this - he was actually very good
Jesus Christ Superstar - also very good
The Producers - fantastic, not only because of Nathan Lane and Matthew Broderick but because of the excellent writing
Mamma Mia - Fun as long as you're not expecting heavy plot.
Hedwig - technically, this isn't a Bway musical, it's off-Bway, but that's just the actor in me being anal-retentive.
A very good show - quite rockin'.
Ragtime - Good performances, but overall, not very memorable.
Kiss Me Kate - borrrrring...
Thoroughly Modern Millie - An amazing performance by Sutton Foster. I'm just upset I didn't see this a second time. It had everything - strong singing, dancing, acting...
Peter Pan - Lots of fun to see Cathy Rigby flying into the audience, above our heads!
Belles Are Ringing - similar to "Millie," but missing the spark that Millie had.
Little Shop of Horrors - not fantastic, but good, and certainly lots of fun!
Avenue Q - Freaking awesome!
Movin' Out - a fantastic expression of dance, and great music - just be warned that there's no dialogue and not a very strong storyline - but terrific performances.
The Who's Tommy - my favorite Bway musical of all time.
Of course, I've seen many non-musical performances on Broadway as well. The only thing holding me back from seeing more is the price. I'm taking my mother to see La Cage Aux Folles in January, and I'm looking forward to that. The new musical "Brooklyn" looks good.
Now I'm trying to think of other musicals I've seen, but forgotten...it was fun to try and list them here!