Boat ramps in the Destin area are pretty well nailed at
http://fishingdestinguide.com/BOATRAMPS.html. I found this thanks to toomanyboats on this forum. She travels to the area too and has some posts on this forum you may want to search. Lots of options, so it just depends where you are staying. I would prefer to launch anywhere near the Destin's harbor. The Joe's bayou launch may be best. It's the one pictured on the top of the cited web page (N 30 24.63 W 086 29.45). Others are the Fort Walton Beach landing (N 30 24.07 W 086 36.24) and the National Seashore ramps (N30 23.52 W086 34.57).
For my little AI, my preferred method of launch is to slide off a utility trailer and onto a hand cart; then wheel the hand cart down to the water (with all accessories pilled on top if the walk is long) and build up the boat in shallow water. I look for spots that lets this happen - park close to the water, manageable seawall, and a place to stand in shallow water. My hand cart has extended runners to spread the load and allow me too launch over a small enough sea wall. I do this single handed, but since you have two, you may be able to hand carry your stuff.
If you can "drag your behemoth" as weinerdog has done, then the southwest foot of the Destin bridge is the closest launch you can get to all the action, however, don't try it unless you get there early. They have parking for about a 100 cars, but it fills up quickly. They have no ramp, but the water is right there (it's about 100 yards to the right of where my boat is parked on the home page photo of my web site).You may want to drive by this site before committing to make sure it is compatible with your methods.
One last tip: places with TI parking for lunch while on the water near Destin are scare. Wall to wall seawall and private docks. Here are some tips:
1.
http://www.destinseafood.com/ - really good food. There is a small sliver of beach parking on the left side of the restaurant that is always available. Stay on the restaurant side of the fence line or one of Destin's founding fathers will come charge down at you in a golf cart.
2. One of the floating vendors on crab island. Great only if you are drunk and hungry.
3. Any restaurant on the coast in the gulf. If the seas permit, you can park almost anywhere on the gulf side beach.
Enjoy,
Greg