According to my husband, the Mandalay Bay is a very nice, mid-range place to stay. The food is very good, they have a cool private pool with a sandy beach and waves (possibly an "adult" pool) and a nice sports book (if you're wanting to bet on your favorite team). Its also towards the end of the strip so it is a little quieter but there is a tram running up and down and it can get you right into the action.
Ditto on the Belaggio being the ultimate in Swank and the Hard Rock is THE place to see and be seen.
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