If you want to drink free, the Ballagio. Was there for Final Four in April, and of the half dozen books we went to, the Ballagio was the only one with free drinks.
I was in Vegas last week and if your looking for 8 seats together at any book you better get there 3 hours before kickoff. I tried going to the Wynn Sportsbook about 2 hours prior to kickoff and every seat was taken. From there I walked to the Venetian and it was just as crowded. I ended up sitting at the bar just outside of the sportsbook at the venetian.
About 3 weeks ago I was at the Gold Coast for the weekend. Not the greatest sports book (and its off-strip) but Sat afernoon there were seats available. It wasn't anywhere near as jammed as the Rio or Palms across the street.