I can recommend Sandestin, which is also right Next to Tops'l, where the State Preserve Park is that another poster has mentioned.
Yes, Sandestin is 'overdeveloped'.
They now have thousands of units per their length of beach.
But, it is NICE!
If you will be traveling anywhere around Spring Break time, and want something a little more upscale that should not be a Spring Break Zoo (like Panama City) then a large, gated, upscale, resort like Sandestin would definitely be worth checking into.
www.sandestin.com
PS: Drive over to Pompano Joe's and spend the afternoon for some good decent food, the most gorgeous sand and water in the area, and even a frozen libation or two.
We have been in May, and absolutely love it.
(except for this last year where the great May Monsoon of 2009 dumped TEN inches of rain while we were there... Not to worry, this is unusual)
Just one caveat about your plans... If you think April means hot sunny tropical beaches, you would have to travel further south. It can sometimes be chilly.
PS: To the last poster, Ft. Walton Beach may be a few miles and across the bridge from the Destin/Sandestin/Seaside area, but yes, it really is a far cry and a big difference.