A nook color is much more tablet like than a Kindle. But it doesn't have 3G, making it much less tablet like if you don't have wifi. :-)
As for wifi availability, you'll have to consider your own usage patterns; I tend to find wifi availability to *not* be pervasive, despite the prevalence of Starbucks and McDonald's.
I.e., if I'm at my mom's house and someone asks how old Einstein was when he died, "Let's drive to McDonald's and look it up!" isn't a great answer.