I do recommend the host we are with right now Westhost. Excellent bang-for-buck. I've not found anything close to them with all the features they have for about $12 a month after setup fee. It jumps up quite a bit for the larger packages, but I'm satisfied.
We have lots of sites with them and the boxes are always up. One time in the last two years for 6-8hours they were out cold, but they were replacing systems everywhere rebuilding and expanding. I'm not sure how many sites they host but I know it probably at least a grand just from what I can see from the various ftp logins. I can't think of a single major feature they are missing. Email support isn't perfect, but I always get a timely - if not terse - reply.
I don't want to step on Brett's toes at all here - I just think it's always a good idea to have a couple options in life
I use pair. They are located in Pittsburgh and they even stayed live for 3 days last year when the power grid was down (diesel generaters). They have all the options you could ever want and they are currently rolling out an account management toolset that is gonna be great.
Support is great and they are hosting over 92000 sites right now. You can get an FTP account for $6 a month and the packages go up from that but all are reasonably priced.
Brett: if you're looking for lease or colocation, you might wish to check out: http://www.cyberconinc.com They've been in the business for ages and their pricing is pretty good. (No, we're no resellers or referral partners of theirs.)