go onto your bridge, go to the turbolift, go to the crew deck, one of the large rooms is your captains quarters with lots of seating and a bed. and if you use your emotes you can lounge on a couch or sleep in your bed....
I'm stuck standing all day in the same armor until the next log in.
you mean the body armor?
if you right click on the armor slot of your character screen (the 'U' button) you can tell it to hide the armor. You can do the same thing with your kit from the same screen. Of course, once you have that hidden, you can change your costume, and create an off duty outfit at the tailor.