Check out Wusage 8.0 at
http://www.boutell.com
It's not free, but it's pretty cheap. I think a server license is aroun $270, and a five-site license is something like $79.00.
Extremely configurable, with very detailed stats. It gives you just about everything you can think of in daily, weekly, monthly and yearly stats.
It might be a bitch to install and configure for you if you don't know a little about *nix servers and apache paths, etc.
Wusage is used by a lot of big hosting companies including Webair
