People told me don't go because kids don't remember - I never thought I was bringing them for them it was TOTALLY for me & so what, good for you. I LOVE that I took my kids & my photos are treasures.
Either make peace with paying for the park stroller or pick up a few umbrella ones and be ok with "donating" on some days - I would leave it with a note and am sure many families appreciated the gift, the whole bus with stroller dance is a fiasco.
If you can tolerate moving around and afford to stay at a MK park on MK day, an EPCOT park on Epcot day etc I say do that. I didn't do this until my kids were around 4 and discovered that nap time can be a pleasant rest if you are near your hotel. The moving annoyed my husband but not me so I guess consider others in your party.
Try to plan out air conditioned rest spots for meals and snacks through that day, nothing worse that having a hungry hot screaming baby and not sure where to go. I always did full service for this reason when kids were little - once I learned.
Bring dried formula you can mix with water.
Bring cheerios in baggies, a fist full of snacks can save most outings.
Bring a few diaper emergency bags, a ziplock with a diaper, a onesie, socks, a few wipes, a single serve of snack.
If you do buy stuff send it to your room, don't try to balance stuff and a baby.
Bring your sense of humor, and be ok with calling it a day if things go sideways