Many or most of them are - I agree. The gay that meant something great when we were younger, as in "happily excited, merry mood, keenly alive and exuberant, having or inducing high spirits".
They always have been fun for me - never an actor or great singer, but a ton of good opportunities for good woodwind players and music directors. Starting with HS kids, through college students and in the pro world - nothing quite like teaching the roles, setting the scenes, polishing the music, generating the cumulative energy, opening night, etc.
West Side Story was one of the first I saw in person - in Manhattan as a HS kid - and was awestruck by the sheer energy and perfection of the performance. Went straight to my bloodstream and have been fascinated by the various great shows and top performances ever since. An art form all of it's own, and truly American.
Bernstein's written music, in general, has never been favored in my case but most of the music in West Side Story is probably his best work - especially rhythmically and harmonically. Couple of lovely melodies, but the underlying harmony makes those shine. He had two fabulous collaborators with him in this one - Jerome Robbins and Steven Sondheim. I have only directed one run of this show, but played it in the pit many, many times. A couple of the woodwind books are very challenging - a lot of quick change doubling on sax, clarinet, oboe, flute. Big fun.
Working in the pit for a running show is a nice 2.5 hour evening (or afternoon) of work and some good steady income. I could probably list 15 or more most enjoyable shows - from the musical standpoint. Directing the orchestra is more work, but also more fun - seeing the stuff on stage unfold. Wish I could do it a few more times.