You mention "traffic". How much bandwidth are you eating in an average month? Is this steady, going up, or going down?
Hosts that advertise "unlimited bandwidth" should probably be avoided, since there can't be such a thing. (There has to be some limit.) Just in general, the term "unlimited" should give you pause.
Shared hosting is probably fine, unless you're doing something very resource-intensive on one or more of the sites.
You might want to check out the support (is there a forum available? live chat? what are the hours of the support phone line? is there a phone line? does anybody answer? etc) before you sign up, as well as expandability (if I max out one plan, is there anything bigger? can I buy extra gigs of transfer? for how much?) and accessories (do they offer a nice cPanel with lots of options? or do they have very few options, and I have to ask, hat in hand, for any of them?).
Going with somebody who's been around for a while is probably a good idea, too. Anybody can set up a server in his garage. And don't be afraid to contact people (by sticky-mail, for instance) for specifics (which cannot be posted in this forum).
Hope that helps a bit.