Been there three times.
Stayed at:
Treasure Island (nice hotel, decent location, but kind of pricey -- I was there on business, so I wasn't paying

).
Monte Carlo (very nice, no real theme or gimmick, just a decent, clean room.)
Bally's (Excellent location, right in the center of the Strip. Rooms were ok, kind of worn, but clean and fairly cheap.)
Tours/Attractions:
Hoover Dam -- I recommend it for a day-trip.
Red Rock Canyon -- Awesome hiking trails, but I wouldn't recommend it in June as there's absolutely no shade!
Freemont Street Experience -- Downtown light show. It's pretty cool, free, and cheesy enough to make you feel like you're in Vegas. A good night-time activity.
The Fountains at Bellagio -- Gotta catch a couple of these shows as you walk by each night!
Shows:
Lance Burton (Monte Carlo) -- Very good show, pretty reasonable price-wise
The Rat Pack is Back (Sahara) -- Awesome show, very inexpensive, but I don't think it's playing anymore.
I wish I could help you on buffets, but I think I've only been to like one buffet, and it was for breakfast. I hear the nicest buffets are at the Paris and the Bellagio.