I was in LAS on business in July and I bopped back and forth between the Westin and the Aladdin (I did two stays at the Westin and one at the Aladdin, and over to the Hilton too). I preferred the Westin because it was a little quieter. It's not that far from the strip and the monorail is close. They had a promo where you rolled dice at check in and you got 10 times the points. Both times the person took pity on my bad rolls and gave me 1200 points, so that was worth a few extra *wood points. My Aladdin room was super-huge, but that was my weekend stay and my Flyertalk friends kept me out all night, so I only actually changed, went out, slept for a couple of hours, showered and went to work.
I'm back for the same conference this summer and I think I'll do the same thing with the stays.