Well, what do we know about Spartans?
Most of them don't interact well with non-Spartans.
Some of them however settle into civillian life after the war.
So, How i see it is they would get R&R when possible, but most of them would choose to stay and train or be put in cryo. Those who do take R&R probably do so in a small group and stay away from civilians. (If nothing else ONI wouldn't want it's best Spec-Ops being humanized to the public eye)
As I have stated in nearly every Spartan thread I've posted in, who is going to say no to a 7 foot walking tank?