I'm visitng my Dad and my 10 year old sister in Tampa and need some suggestions on fun things to do?

I'm 33 and my half sister is 10 so what can we do that we would both enjoy? I'm going in mid March. Are there any festivals going on that time of year in the Tampa area? We went to Busch Gardens last time which was 3 years ago, are there any new attractions that just opened there? Will it be warm enough to get tan? Where are the coolest shopping areas? Are there any amusement parks besides Busch Gardens and Disney World that are not too far away?