I would love to as well - it's quiet and you can take a break to read a book whenever you want.
The problem with our library is that even though they have a 100mb internet connection, they filter everything. You can't use Git or SSH for example, so it does me no good as a place to work.
(There's an Enoch Pratt branch directly across from my favored coffee place in Roland Park, which would be just dandy if it didn't have the weirdest opening hours known to man. Closed on Thursdays and Sundays? Who does that?)