I'm a guide about an hour south of there in Sarasota. April is a great month. Water is warming and everything is kicked into Spring gear. Snook fishing will be picking up well, by then. Redfish won't be schooled up in big schools, but will be in pods and singles and should be feeding. Trout, ladyfish, and bluefish will be all over the grassbeds and edges. Tarpon won't be there yet, though.
The only caveat is the wind. March and April are two of the windiest months of the year and it can blow you out easily. It's hard to hide from it in many situations and 15-20 and gusty on open water isn't ever fun to fish in. But, if you catch it right for the wind, April is great!
Tampa/St Pete is a great area with ALOT of water. Look up Capt. Ray Markham. He's one of the very best up there.
Best -
Andy