I was in your boat. Here's what we did with our 4-yo and 2½-yo sons...
We brought our Duo-Glider stroller (front and back) and it worked great. Seeing that you'll be at the GF, you'll be able to roll the stroller right onto the monorail. Yes, those strollers fit just fine! The bus rides get a bit trickier because they are bulky but we would definitely do it again. It gave a lot of extra storage on the bottom, great sun shades, and we even bought a rain poncho specially made for it. That came in handy a few times. Nice having a dry stroller and it even allows the kids to be inside and stay dry (it's ventilated).
Also, while at the Orlando Airport, we were able to bypass the huge security line because we had the double stroller. They led our whole party to a line with noone in it. Ahh, that was great. I think I'll bring the stroller on all trips just to bypass that line...lol.
~DawnMaree