I rarely spin - we don't have decent classes around here. I ride a little but normally do stair climbing on a step mill, running and weight lifting. Lungs definitely take a couple of weeks to get back in shape. Legs are pretty good as I do riding-related weight lifting (e.g., squats, lunges, seated ham curls).

Personally, I think a break from the saddle is good. Not just a physically. I need a mental break too.