Anywhere, with anybody that will go with you. Redfish can be found just about anywhere on the Florida coast. Mosquito Lagoon has the reputation for the biggest redfish and an abundance of fish. I am a Gulf Coast guy myself, so I favor the west coast of Florida.
If I were planning a trip, I would go to the 1,000 islands area around Naples/Marco Island. It is a great redfish spot, as well as, just about anything else you can think of. It has the widest variety of habitats you will find in Florida. The only guide I know down there is Capt. Charlie Wright. I runs flats boats and kayaks and knows the area as well as anybody.
http://www.chokoloskeecharters.com/
I am in the Tampa Bay area and there are a lot of good redfish spots here. April is a great month since most of the fish are moving from winter to summer haunts, so there is a lot of activity in all species.