i would definarely hire a car,it is so much easier.i personally couldn't think,of anything worse,than having to hang around,waiting for buses,after a day at the parks.
i also think,doing the parks everyday,is too much!
it is nice to have rest days & just chill out.you could drive down to the beach.the beaches are lovely,i personally like,st petes & clearwater,although we have drove down to miami.
shopping is so much easier,with a car as well & believe me,you probably will shop!
will you need a 3 week ticket,if you are getting a flexi ticket or are the prices similar,for 14 & 21 days?
i just love the freedom,of a car,but that's just my opinion,but as already said,theres alot more to see,than just the parks.
but that is what planning,is all about,so have fun planning & keep asking your questions,as it will really help,with your trip.
tracy