I'm in a mediocre classic rock (and country, motown, 80's) cover band. We've been gigging regularly about once a month at local bars/restaurants for three years now. We don't really have a CD or promo material. What has worked for us is a two minute live youtube clip that has snippets of four or five of our better songs...honestly I don't think a bar/restaurant owner is going to spend any more time than that listening to anything you give them. We have a regular crowd that comes see us...and this is the key to our success. Like someone else mentioned, yes, the classic rock audience is "old" (eg. 40-50) and goes to bed early, but they are also grown ups with jobs who have no problem spending $50 or whatever for a night out. If we got a weekly Wednesday night gig could we consistently count on them coming out? Absolutely not.
Anyways, I guess what I'm saying is bringing an audience is more important than website, CDs, etc. if you are trying to play bars/restaurants. If you're going after private gigs, weddings, events, then that's another story of course.
As a point of reference, here we are at one of our regular gigs: