Atlanta's best downtown attraction for kids is Centennial Park, built for the 1996 Olympics and now open throughout the year.  It is just to the west of the heart of Downtown, and it is a great place for a daytrip!   The Park is relatively small, and it's primary strength is easy access, surrounding attractions, and the beautiful Olympic Rings Fountain.  Here's the best way to enjoy the Park in summer.

  During Atlanta's summer days, you have to be aware of the heat.  It is always extremely humid and hot.  The Downtown area is as paved over as any borough of New York, which makes things worse.  The first thing you do to avoid the heat is to use MARTA, Atlanta's small subway system, to get to the Park.  Your car's radiator will be eternally grateful.  You will also save lots of gas money, parking money, and sanity (the local parking lots are exorbitant, distant, and hard to find).  Simply find the station nearest to you, pay your admission, and ride the trains Downtown.  MARTA gets a lot of bad press from one-time users who have a bad experience, but regular riders find to be a great service.  New Yorkers tend to give it higher marks than their own system.  For a daytrip that includes playtime in the Fountain, bring good towels and wear your swimsuits as casual dress - all of the local attractions will allow entry to you in this gear.  You should exit MARTA at the Phillips Arena Station, or the W1 (Western Line No. 1) station.  Depart the train and follow the signs to the street.  Cross Marietta Boulevard carefully... and there you are!  Let the kids play in the water for awhile (don't forget the sunscreen lotion).  When they are ready for a break, give them a snack, or have a picnic, and then head to the northern end of the Park.  This is where several nationally known attractions are located (my favorite is the Imagine It: Children's Museum of Atlanta, and I'll post a tip all about that later).  DO NOT go to more than one of these surrounding attractions in one day - you'll end up with "tourist's foot syndrome," brought on from hiking six miles in one day in bad shoes while trying to see everything.  You would need a gigantic wallet to be able to afford it all, anyhow.  PICK ONE, and enjoy.  When everyone is done with the attraction, head back to the Fountain for a refresher dip!  Get in with the kids, you'll need to cool down, too.  Finally, cross the street carefully and ride MARTA back the way you came.

Any daytrip should be scheduled to get the kids indoors at the Children's Museum or other attraction during the sunburn hours of 1 p.m. to 3 p.m.  Alternatively, if you just want to spend a couple of hours downtown, bypass the Fountains, and enjoy the surrounding attractionswithout touring the Park, get off the MARTA at the Peachtree Center (N1) Station.  Walk west, following the signs down Baker Street, and reach the northern end of the Park in a matter of minutes.  But don't let the kids see the Fountains, or they'll be raising holy Ned until you let them get wet.