I never worked Besse, but TMI has a pretty good walk. The contractor lot is on the southwest end of Unit 2 (the dead reactor) and you have to walk all the way from where your car is to the Unit 2 fence, the entire length of both units, and then east to the gate which is near the northeast corner of Unit 1. Some people put their bicycles on their car rack, drove to work, then rode their bike to a parking area close to the gate. There were even a few well-beat-up bikes that were just left there and if you were lucky (and so inclined) you might find one to ride.
Calvert Cliffs had one parking lot that was used only for big outages that required a bus ride to the gate.
Turkey Point has a contractor lot that is long and narrow and perpendicular to the plant, so if you have to park at the far end it is a good hike.
I also remember DC Cook being a fairly long walk, but that just might be because it was so damned cold and windy.