Here's a link that provides info on comps and room deals at the leading Vegas poker rooms. Basically, the comps aren't anything to write home about but are better than nothing.
The real benefit is the sharply discounted room rates at places like the Bellagio and Wynn, which can be worth hundreds of dollars per night. In addition, sometimes rooms are available through the Poker Rooms when they are otherwise unavailable to the general public.
The line passes, in my experience, are also worth a lot because they save a lot of time that would otherwise be wasted standing in line.
http://www.pokerkicksass.com/RoomInfo.html