Oh -- general advice -- if you intend to do any gambling for any length of time, get a "comp card" and use it. You may as well get something out of the losses, and a free meal beats nothing (except at the C-C).
Shows and Rides:
Free:
Pirate battle, outside Treasure Island
Volcano, evenings outside Mirage
Waterfall, daytime outside Mirage
Dancing water fountains, outside Bellagio
Light show, Fremont Street (downtown)
White tigers, inside Mirage (display area)
Nice big fish tank, inside Mirage (behind checkin desk)
Nice big shark tank, inside Mirage (the casino, of course)
Huge golden nugget, Golden Nugget (downtown)
Low-cost:
Dolphins, at the Mirage
"Big Shot", top of the Stratosphere
old cars, Imperial Palace (sometimes free coupons are given out TO COUPLES ONLY)
Oreo, First Rabbit of Magic, Lady Luck (downtown)
High-cost:
Blue Man Group - Luxor
"O" - Bellagio
Siegfried & Roy (tigers) - Mirage
Cirque du Soleil - Treasure Island
rock music concerts, various - Hard Rock