We stayed at Caesars Palace. Lovely hotel, but personally I hated the whole Vegas 'thing'. I think you either love it or you hate it, and for me it was, sadly, the latter. I think you have to be a certain type to like Las vegas, and that just wasn't me.
As I say, the hotel was pretty amazing, specifically the food, which was out of this world. There's SO much choice!
We used Trip Advisor and Expedia when choosing our hotel as there are literally thousands of reviews - good and bad.
I wouldn't advise staying off the strip, though. Some friends of ours did and taxis were quite expensive to ferry them around. Our hotel had free parking, so it might be worth looking into that, as Las Vegas has more to it than just 'the strip', which can become a bit overbearing.