I find myself really hurting for recuperation. It only comes from the 2.5m cupola and is a must have on a long trip. Even a mission to Duna or Eve needs the ship to be festooned with cupolas like it has a pox disease so that my crew can survive.
I've modded the SSXP parts so the greenhouses and aquaculture modules provide a bit and like the results. Any way you could add it in to the main download? In my head canon, the fresh food and opportunity to garden or tend to the animals is relaxing enough to match looking out at space from a cupola. The 3.75m parts support 2 Kerbals each and the 2.5m one supports one, so carrying one of each lets me keep 8 Kerbals at around 45 health permanently. That let's me do a few days of ops away from the station/mothership without needing to worry they'll die or spend forever recuperating for another excursion.