join the Starwood Preferred Guest (SPG) membership. I may be too late to collect the points but you could look into getting a Starwood AMEX card. They usually award some points for just opening up the card and some for when you use the card the first time. Once a SPG member (and after you have your SPG number on your reservation - call the Dolphin and have this added), you can request an upgrade on the SPG website.
Once you get there, be very nice, polite and request an upgrade. Request a balcony with a great view of Epcot and see what happens. THe staff at the Dolphin have always been great and am sure they will do anything possible to help you out.
Have a great time!