True there are a few Races that have very very specific needs ad may draw a ship fully crewed by them, but the vast majority can deal with standard enviroments. Vulcans have been known to have their personal Quarters and even work stations set to Vulcan gravity, with their quarters being set to Vulcan temps.Same with andorians and with the advent of the holodeck, they can take a quick 2-4 hour trip into a full enviroment of thier choosing to reregulate themselves. ZI'm sure sympythetic captains would have their shifts shortened or split to accomidate such cultural needs.
Although we have to also remeber by TNG, CRews were 90% human, as other races were regulated to back seat roles.