Most people programming in National Labs get offices, though you might need to share with one person. If you are in the bay area, think about SLAC or LBNL.
Depends on where in SLAC you're working. If you're in the IT building, you'll frequently need to share a larger room with 3-5 other people.
Similar experience where I work (FFRDC). Most people have their own offices, although some of the more desirable offices (ones with windows that are also bigger than interior offices) are shared. It does get a little sardinelike in summer when interns need somewhere to go.
Laurence Livermore National Laboratories is not too far from the bay area as well.
At NASA we tend to have 2-3 person offices. But it's a big agency so YMMV.
Not always true from my experience at ANL
I know for a fact LBNL Software Developer 4 pays less than half the salary of other software companies.