If paying top dollar: PIAZZA, SWEENEY, DRS, CHICAGO, SPELLING BEE, PRODUCERS and SPAMALOT. You seem to like sharper, funnnier shows so maybe try to see SPELLING BEE or DRS. SWEENEY is a must simply because it is Sondheim at his very best.
If paying 1/2 price consider: SWEET CHARITY, HAIRSPRAY, or FIDDLER. You like some of the classics though the only one now running is FIDDLER and if you have never seen it, maybe you should.
If getting in free or cheap maybe see MAMMA MIA, PHANTOM OF THE OPERA, LION KING, CHITTY CHITTY or WICKED. None of these are as strong as they could be. LION KING is amazing for Julie Taymor's staging but as a 2 1/2 hour show it does try your patience. Still it is the least offensive of the lot.
Whatever you see I am sure you will enjoy!!
Cast albums are NOT "soundtracks."
Live theatre does not use a "soundtrack." If it did, it wouldn't be live theatre!
I host a weekly one-hour radio program featuring cast album selections as well as songs by cabaret, jazz and theatre artists. The program, FRONT ROW CENTRE is heard Sundays 9 to 10 am and also Saturdays from 8 to 9 am (eastern times) on www.proudfm.com