There are a handful of coffee shops that actively don't want to be used by laptop/tablet users, and one way they signal that is by not offering wifi. It's not quite as effective a deterrent as it used to be with the advent of cheapish mobile data plans that have tethering, but it can give you an indication of what the shop expects its usage to be. Fins Coffee in Santa Cruz, CA is an example of a shop without wifi.
Given how heavily Starbucks not only offers but advertises its free Wifi (as does McDonald's), my guess is that they do actually intend their stores to attract laptop/tablet users.
Funny you should mention Santa Cruz, as I've also noticed there's a variety of styles of coffee shop in the area.
There's Verve downtown, where low table-density in a big room with a high ceiling creates islands where patrons can isolate themselves from one another. I'm guessing this makes it a place where (mostly young?) people can be productive on their devices.
Then there's a place like Lulu's (right across the street!), that's more cramped and has a more traditional/low-light ambiance, where it's basically impossible to ignore the people around you (I hope I don't make it sound like that's a bad thing).
Yeah, I used to live there, and I think it might be my favorite coffee-shop town. Lots of places and variety, especially considering the modest population. My own favorite one is probably Mr. Toots in Capitola (2nd story, & has a small balcony with ocean view).
For folks who are away from home, or otherwise on the road with a laptop, Starbucks is invaluable. There's a guarantee of transactional access to wifi, even though the quality of the wifi varies by location, and the only risk is finding a seat. I dislike hogging the tables at coffee shops near my house to work, but do so occasionally to help myself think -- but when I'm away from home I find Starbucks a very useful place to go and I'm not always near a local library or other alternative.
Given how heavily Starbucks not only offers but advertises its free Wifi (as does McDonald's), my guess is that they do actually intend their stores to attract laptop/tablet users.