For those who dig public pools in the city, the exciting news of the season is the new pool renovation at Piedmont Park. I walked by it before it was open and it looked phenomenal...both the pool and renovated bath house. The Grant Park pool is also surprisingly a great spot. It has a separate children's pool and a large adult area. The strapped down lounge chairs do remind you that you are in the city, but none the less, it is only $4 and you have the trees, sports facilities and animals of neighboring Grant Park and Zoo Atlanta.
I can't comment on the Candler Park pool, but it is another local spot along with the Martin Luther King Center pool, but that one is all indoors. Access Atlanta was nice and complied a complete public pool listing in and around the city if you want more options.
Of course, there are plenty of condos and apartments with pools if that is your crowd. It just can be nice to mingle with the community outside of those settings. You can always "Shoot the Hooch" as well - tube/raft/kayak/canoe down the Chattahoochee, which definitely puts you more directly in touch with city.
My other pick would be to check out some of the local hotel pools. The historic Georgian Terrace Hotel has a rooftop pool...plus it offers Midtown nightlife and the Fox Theatre right outside the door, so you can book a room, have a pool with a view and plenty to do. Atlanta.net actually has a great listing of local hotel deals and packages that include local attractions. The hip W Hotels even offer a 20% discount to locals (plus see the picture above for their swanky 16th floor pool at the downtown location).
Don't forget, whether you are chilling at the public pool or crashing a local hotel pool, make a stop at the downtown Hilton's tiki bar Trader Vic's to add to that exotic, tropical vacation vibe. I also wouldn't miss a Braves Game, or at least catch a drink or dinner on the patio at Six Feet Under midtown (the Georgia fried catfish is pretty tasty) where there is an amazing skyline view where you can also see fireworks from the baseball game if it is a winning night.