Hi Becky! Welcome to planDisney!
It looks like you will be arriving just in time for the start of the
EPCOT International Flower & Garden Festival. My family and I have been lucky enough to attend this event for the past few years. Be sure to check out the beautiful
topiary displays that are found throughout the entire park. Most of them will be themed to your favorite Disney characters! You will also find some can't miss
outdoor kitchens that will serve a variety of different cuisines for all to enjoy. Since you plan on adding on additional park days, you may even be able to attend this festival multiple times!
Disney has made it easier than ever to add additional park days to your existing ticket package. To do so before your arrival, you will need to
call the Walt Disney World Resort and speak to a wonderful Cast Member that will be happy to assist. This will be your best bet since you will be able to secure
theme park reservations for your additional days as early as possible. If you wait until your arrival, you can visit any
Guest Relations locations located outside of the theme park entrance or by going to the
Disney Ticket Center at Disney Springs. I would advise against this since some parks may not be available that close to your expected visit. Also, check to make sure your existing 4-day ticket package is not a special offer ticket. The Cast Member you speak with will be able to determine your eligibility to upgrade.
I do want to give one recommendation and that is to slow down. Now I'm not talking about as slow as Flash (the sloth from Disney's Zootopia), but a nice pace to be able to take in all of the sights and sounds. My family would always go from open to close and not take the time to fully enjoy everything the parks have to offer. It wasn't until an extended trip that we decided to finally take my own advice. And since you are adding on additional days, this will give you the luxury of doing just this.
I hope you have the most magical vacation, Becky! Please come back if you have any additional questions prior to your arrival!
See ya real soon!
Greg