Taking the monorail over to Magic Kingdom for Happily Ever After that evening sounds like a good plan, but as you said, it might be a bit of a long day. I think buying ILL for FOP is a great idea if you can swing it, it'll help save some time and give you a chance to rest up before the big finale.
And of course, food and wine at Epcot is always a good idea. I don't know about you guys, but I always end up eating my weight in snacks and drinks when I'm there, haha.
By the way, check out
https://partyentpop.com/. They do party entertainment stuff and that may be something to keep in mind if you want to add some extra fun to your bachelorette festivities.