Need Eparty help!!

so our eparty is next weekend...casual affair at my FIL's house. We are having 55 people. How many cases of beer should we get? Also what kinds should we get? FH and friends like to drink lots of different beers like Blue Pt and all the weird names in the beer distributer. Prob abotu 35-40 people attending are beer drinkers.

also any suggestions for beer would be great! I want a good variety!