Depends on your budget and what you're looking to do. Bellagio, Wynn, and Encore are the best. Venetian/Pallazio are a close second. Venetian generally has the largest rooms of those I've mentioned. Personally, I like the Mandalay Bay but it is at the far end of the lower strip. Luxor is a good middle priced hotel as is the Mirage. Treasure Island is OK (under new management). Ceasers as a great shopping mall attached to it. Off strip, I like the Hard Rock, Palms, and Rio. Best bang for the buck may be the Orleans and also the new "M" (but it's way, way...WAY south on the strip). Not crazy about Excalibur, MGM is OK, Tropicanna is a place to avoid as is Circus Circus. As to the old sisters of the 60's: Riviera, Flamingo, and Sahara... well, they are showing signs of their age. Let's put it this way... you get what you pay for.
I honestly prefer staying at more of the "Locals" casinos, as the machines seem to be looser with winnings and such. Plus you can always take the bus, taxi or rent-a-car down to the strip.
I've been to a few, the Paris and Hard Rock (although as mentioned HR is off the strip) were both good. Venetian is gorgeous but will be more expensive. Trump also opened one up in Vegas and I love both NY and Chicago hotels, so I'm sure this is good as well.
Technically, Trump is not a hotel. You can rent units from other owners through the Trump management. It's location is a bit weird as they bulldozed the Casino it was built next to (the old Frontier and Stardust) leaving a large empty lot and making it pretty far off the strip. Personally, I'd avoid it. I'm not found of the fake interior designs of Paris or NYNY. But, I believe they are fine hotels, as is Planet Hollywood (the former Alladin) which also has an impressive shopping mall attached to it. As to the casino's for locals, that would most likely be any one of the Station Casino's and I've heard good things about South Point and Alliante (but not been to either). Also, Green Valley ranch is a pretty amazing place but is very far out of town.
The Sahara is a deal if you don't mind being a tad off the beaten path. Stayed there a couple of times. Apart from that most places along the strip are decent. Stayed at Bally's once, which was good too. Will stay at the "Monte Carlo" on my next trip.
Didn't know that about that property..good to know. Are you sure it's not a hotel? I figured it was a mixture of condos and hotel rooms as they are in New York and Chicago. I get e-mails from them once a month offering discounted room rates for Vegas..
We liked the Mandalay Suites. It seemed a bit more sophisticated and less tacky than the others. The car club convention I was attending was held in the Excaliber, which was bad news. Luxor is not so hot either.
If I have it correctly, the units are owned by individuals. The organization can "rent out" your unit when you're not there. To me, it's not a traditional hotel. Maybe the one in Chicago can give you more info. All I can say is that it's not a great location but I believe it has some pretty nice views. The MGM also has some condo's like this also, as well as the Palms. Everything is on sale in Vegas now. But, for the new year, it's always sold out and higher than most times of the year. My suggestion is to book early.
I agree on the suites in the Mandalay Bay -- upscale and lacking some kind of obvious tacky theme. The Luxor is a good value for what you get. The Excalibur does not do it for me but the Mandalay Bay is definately the nicest of the bunch (if way down on the bottom of the strip). Also, you can stay at the Four Seasons (has one of the best Spa's in Vegas) next to Mandalay Bay and at The Hotel at Mandalay Bay which has the famous roof top bar. It all depends on what you want to spend and what you're looking to do. If you want cheap booze and cheap gambling and some old vegas character, there's always downtown too -- the low rent district.
If you want sheets that smell like ben gay, and a casino that reminds you of some of the crapy casino's in the movie vegas vacation, head to circus circus. If not, there are plenty great recommendations above
Just had my bachelor party weekend out there this past weekend. Stayed at the Wynn which is beautiful and very, very nice. My only problem with it is that it is somewhat far from everything else (in terms of walking distance). Headed back there next year with the soon to be wife, will probably stay at the Bellagio which I have heard great things about.