We have traveled twice to Disney with an infant...older dd was 3 months and younger dd was 6 months last July (we also have two older boys, so that is why the girls have traveled when they are so young). We used the same stroller both trips, and for us it was ideal. It is an older Combi stroller we bought 10 years ago for first baby. Several key feautures for us:
1) Stroller has a full recline...completely flat. Leg rest area elevated, so the area was roomy for an infant and allowed baby to get comfortable.
2) Stroller handle moves from front to back...alowing you to face baby or to have baby facing outward. This was such a wonderful feature and I wish more strollers had this! It not only allows you to vary the viewing for baby, but it also gives you so much more flexibility for sun protection because the sunshade also moves from front to back and you can use the angle of the sun to your best advantage.
3) Stroller was light (about 15 lbs) and folded easily to a standing position (I hate, hate, hate how the Gracco we have folds up on the tray!). We were able to navigate airport security and Disney trabsportation easily.
DD will be 20 months for our next trip in September, and she is too big for that stroller. It has taken me literally months to figure out what stroller to buy for that trip LOL Poor dh just shakes his head (with 4 kids we have owned our fair share of strollers

. I will sell the old Combi at our next yard sale, but I will be sad to see it go - like a piece of my kid's babyhood.
I have already rambled quite a bit, but I just wanted to add that we did use the stroller fan last trip for infant dd and I highly recommend it. With older dd we used an infant carrier and she was happy to travel in it at spells. However, younger dd never liked being snuggled in the carrier and in the July heat of Disney there was no way she was having any of it.
I have seen people using the full travel system with stroller and car seat, but I would not recommend that...so hard to travel with unless you are exclusively driving. Do you take the carrier into shows, restaurants, etc and where do you put it then and what if you leave it outside and it rains? Plus, I would be worried about the heat with an infant in a car seat in warmer months.