Manni, Dressage and jumping are always welcome; these are familiar equestrian endeavors, and always a joy. I love your other suggestions, too!
Polo, yes! I play at home, and it’s incredibly addictive-- it’s pretty funny that the nicest people are sometimes the most aggressive players. http://www.sarasotapolo.com/polo/learn.cfm
I have lived in Florida my entire life and have never gone beach riding! The one listed above looks really nice; I saw another beach riding outfit in Bradenton that might also be good. http://www.beachhorses.com/
I also found a barn for Saddlebreds and gaited horses in Tampa, something I have always wanted to try! http://fivegaitstables.com/
South Creek Foxhounds won’t quite be in season during my trip, but it definitely belongs on the list http://www.southcreekfoxhounds.com/
I just love trying different equestrian sports-- I have never tried working cattle, driving, reining, speed games, gaited horses, or vaulting-- all of these are on the bucket list.
Not to mention the great venues I want to visit! Rome, Aachen, Spruce Meadows…