Barnes & Noble loves it when you do this, because their statistics show that the more people read in the store, the more books they end up buying.
Borders isn't quite so upfront about it, but they're cool too. Most comfy chairs are near the kid's department, but you have to deal with bratty kids.
I do a lot of reviews & research and I spend a lot of time in both stores, generally in the cafe with a small coffee, reading stuff. Both stores are very nice.
P.S. My son, a fellow anime/DBZ lover, has been doing the same thing, only he's sitting on the floor in front of that section, so he can just reach up and grab them. Lazy teenager. If you visit our local Borders and see a kid doing that, say hi.