My wife and I have used the Plant City Range mentioned earlier and Family Firearms range in Valrico. Both places are good. We are members at the one in Valrico, because it's half way between our home in Plant City and where we work in/around Brandon. It also has a great group of folks working there and they charge by the lane instead of by the person, which works great for my wife and me.
We have also been to Tenoroc in Lakeland which is a nice outdoor range, that also does archery and clays.
Here is a link to Family Firearms - http://www.familyfirearms.net/
and one to Tenoroc - http://www.tenoroc.us/
I haven't used the shoot straight range in Lakeland, but we have bought guns there and the folks were super nice.