We have a sit and stroll and we love it for being a car seat but our daughter rarely sits in it because she's not a stroller kind of child in first place. When we went to Disney, we brought it along but she hardly sat in it. Also, we stayed in a Disney resort so it was a hassle carrying it on and off the shuttle bus. When it rained and we went inside certain attractions, strollers were not allowed so we had to cover it or it got wet.
The Disney rental prices were actually reasonable. You can also get a multi-day discount, if I recall correctly. They also have multi-child ones so you can put 2 children in them, or put your diaper bags and other supplies in the empty seat if one child decides not to use it. Those bags get heavy after a while! Yes, you can bring snacks and juices and those get heavy too! They are the plastic type with no padding so it's not totally comfortable but your five year old would probably appreciate it when she gets tired.
A Disney staff person actually suggested that if your child doesn't like sitting in a stroller by herself, you can rent a wheelchair and have her sit on your lap while someone else (your husband perhaps) pushes you. I thought it was brilliant but I didn't do it. Just thought I would throw in that thought though.
The parks are big and I myself got tired. I would also suggest spacing things out and not try to catch every single attraction in every single corner of the park. If there is something you can skip, don't sweat it. Plan out your route so you are not rushing from one end of the park to another. That way, the kids AND adults won't be too tired and the stroller issue may be less of an issue. There are plenty of places to stop and rest, indoors and outdoors, but I think a lot of time, it's the time factor that keeps families moving. Using the fast pass also helps eliminate waiting time in line. It's a coupon that you can collect (make sure you get one for each person) so that you can go back at a specific time and wait in a shorter line.
Hope this helps.
