Depends what you like to do. I've stayed at the Bellagio and the rooms were great and it's in a good spot on the Strip. Aria is the latest new place folks are buzzin about. Twice on a budget I stayed at the Motel 6 on Tropicana Ave across from the MGM and it was fine, not too far a walk from the Strip (2 large 'blocks')
The Tropicana Hotel, on the Strip and at Tropicana Ave I've heard is good value, even if it's lost it's heyday luster. Believe it or not, I also heard from several people that Hooters rooms are great and well priced.
One of my face stays however, was unintentional: I bid on Priceline for a 4-star hotel and landed the Trump Hotel. It's off the Strip but only a 5-minute walk to it, but there are no slot machines or gambling frenzy etc in the lobby as you'd get in the other Strip hotels, which was actually nice respite. It was a peaceful hotel, with a nice pool, poolside restaurant with healthy breakfasts and the rooms were fabulously comfortable and ample. about 8 years ago
Tuscany. About a 30 minute walk to the strip. Between Hard Rock and the strip. Amazing rates AND free food and drinks! Amazing Mexican food in there. Money goes a long way. Otherwise, Golden Nugget downtown is old school but upgraded. Outside of that, a MILLION choices. All good. about 8 years ago
We stayed at Polo towers...right behind Planet Hollywood...no casino to walk through, and very quiet...the perfect location! We also stayed at the Mirage...beautiful but a Very long walk to the room...every hotel on the strip has a massive casino you have to walk through to get to the hotel...very annoying at the end of a long day. about 8 years ago