The FR is a private members only club within the House Of Blues (except Vegas, it's on top of Mandalay Bay). Its usually connected to, or close to the green room. So you can sometimes rub elbows with the artists after shows while they "unwind". The dining is usually 4 star and there is typically a lounge/bar area with other private rooms surrounding. Its a a very dark and artsy atmosphere.

1 night access, means they will let you in for 1 evening to see if you like it. Memberships usually start around $2k, you get first rights to tickets before they go on sale, special events with artists and some other things. The only other way in is if a member invites you. Or, as I said, sometimes you can get on the guest list if you call and act interested in a membership.