Hi again, Carolan! Honestly, I like to spend two days at Epcot and I've been there many times. It is the largest of the four parks, and there is so much to take in. It is twice the size of Magic Kingdom Park!
Epcot is really almost two parks in one. Future World and World Showcase could each take up most of your day. If you can easily pick a few things and plan your day, you'll be okay. If you want to see it all, I would definitely dedicate two days. Alternatively, you could always do one day and catch the rest on your next trip, right? Of course, everyone has their own opinion, just giving you mine! Many think of Epcot as an adult park but my own kids request at least two days there.
I hope this helps, Carolan.
I wish you a MAGICAL vacation!
-Jacqui