I keep mine at 1.026 at 80 degrees there are a lot of different answers to that question though alot of it is choice though
most LFS keep salinity down to help the fight of parasites and diseaes. some people want to keep it closer to natural seawater.
the main thing is whatever you keep your SG at is to make sure you acclimate everything properly before adding them to your tank.
HTH
Mike