My DH does not enjoy disney as much as me, DD10 and DD6. So we go alone at least 2x's a month. I bring my stroller. I feel safer w/my stroller If DH is not w/me and we go into a shop or if we are eating CS. Disney world is a very big place w/lots of people it takes only a second for a young child to wonder off (I've seen it).
What we do is bring stroller and park it at every park. Ex. we'll park stroller by Buzz lightyear ride and do tommorowland. When it's time to do Mickey's toontown she'll get in stroller and I'll drive her their. Also DD6 likes to look around and take everything in. When it's 100 degrees and your DD6 is staring at those big balls they try to sell, Disney is not fun.

SO, You want to go indoors and what better way to do it then to have your DD6 be pushed right by those money breaking balls.
A funny story; Last year DH, DD9 (at time), DD5 (at time), and me,were going on our week long trip to Disney, I had bought a very nice, very expensive maclarren sroller for this trip. Like you I thought it would be cheaper to buy then to rent. Well we live outsife of tampa so it only takes about 45 min. to get to the world. Half way to Disney I realize I forgot my stroller.

DH was only driving us their and staying the night (remember disney is so much more fun without him). Well, he refused to turn back and bring us the stroller. I ended up renting a stroller.
The DIsney strollers are very easy to push, and if you are planning to stay all day in the parks I suggest you get them. They will also give you a small discount if you rent for more then 1 day.
Also, are you flying down? Because it might be easier for you to get around the airport w/ a stroller. Also are you staying on property? I've encountered many nice people willing to help w/ the stroller on and off the bus.
This year we will be their for
free dining and I am planning to take my stroller. If I don't forget it.
Sorry if I've given you to much info. but I think a stroller is great!! Heck if someone could push me around I'ld let them. And believe me I'm not lazy.