I have a similar experience. I work full time for a BigCo, so I have to work at finding spots off campus where I can go and comfortably code for an hour or so during lunch. It has been a non-trivial venture, living in a not-so-tech-friendly area.

After a while, I become apathetic to the place I am working at over lunch and need to move to keep interest... else I will just decide to skip the offsite work and sit at my BigCo desk and vegitate.