I live in Las Vegas, and Hilton is by far the largest. If you want every possible line, including every total and half time lines on college games you have to go to Hilton (even they dont offer everything), or the Binions new sportsbook or luckys on freemont street. They are tiny, funny looking, yet offer the most lines I have seen in town. If you are just going for March Madness games then the Hilton will offer you all the lines you need. Venetian, although I believe the nicest hotel with the best poker room and best restaurants has a crappy sportsbook, MGM is just garbage and tiny, Ceasars palace, nice sportsbook, and poker. Nice restaurants and centrally located.
There you go, from someone that actually knows and goes everyday.