Get a simple one.
Don't get the Cobra 75WXST. You know, the all in one CB thing. The speaker on it sucks, and it's more expensive than a simple one.
You want one with a volume control, squelch, and a channel knob. Not much else. That'll keep it simple for trail rides and road trips. Uniden, Cobra and Radioshack all make fine examples of these.
That's my 2 cents. If you want something more capable than that, you're spinning your wheels with the CB. Start studying for your HAM....