I try to keep my water around 76-78. When my tank hits 80, my gsp starts to close up a little so I try to keep all my corals happy. Safe range is something like 72-82. 80 would be fine but to me is a little on the warm side.
Mine usually ranges between 78 and 82. It's hard to keep the temperature low when I'm running 1200+ watts of metal halides... I don't even use a heater. And that's for 300 gallons of constantly moving water. I would like my temps to be lower (ideally), but there's only so much I can do, short of buying a chiller.
Try to keep your temps within a couple degrees in a 24 hour period. Drastic temp swings are worse for your tank than consistently high or consistently low temps.