I tend to be very warm and generally dive in shorts and a rash guard for warm open water (above 76 F). What I wear to the pool tends to depend on how long I anticipate being in the water. For a half day of in and out of the pool, I wear a long sleeve rash guard and a pair of neoprene shorts with pockets. For full days, I wear a 3/2 full suit. Obviously the chlorine will destroy everything over time so I tend to use "budget" suits.
Our local swim shop turned me on to chlorine resistant swim suits. They are definitely not beach wear, but they are under a rash guard and shorts or a suit so it doesn't matter. and they last two or three times longer than the regular swim suits I was using. At work where I am in saltwater I prefer Nike swimsuits as they just seem to fit me better and hold up okay.
YMMV,
Jackie