There is plenty to do even if you don't gamble. the first time Billy and I went we only gambled with like $10. the second time we went we still only gambled with like $200. The trick is to do the cheap stuff so you can make it last long.

Things to check out when you go:
Red Square at Mandalay Bay (restaurant and really cool vodka bar)
Commander's Palace at Aladdin (upscale restaurant)
Bellagio Hotel (so beautiful)
Venetian (they have really cool gondala rides)
Cheetah's (best strip club ever)

There's so much more I just can't think of it right now.