Not sure what special accomodations you may need for him, but we just returned from WDW w/my dd2. We purchased a Jeep umbrella stroller and it was a life saver. We needed it though the airports, it reclines, had a sun shade, and 2 storage bags on each side. The best thing was the umbrella fold very easy and small for bus/boat. We purchased at walmart.com for about $50 total with shipping and all, less than we would have paid to rent a stroller @ WDW!
Congratulations on your upcoming adoption! We're an adoptive family too
I'm still in love with our Peg Perego Pliko P3 - our DS is 2 years 4 months and we still use it quite a bit, especially now that he doesn't want to nap at home but still needs a nap - he falls asleep in the car and we put him in the P3 and do our shopping and errands on the weekends and he's really comfy in it. The P3 reclines all the way, and is nice and big in the seat area, so it might be something for you to look at for your DS post-surgery...you didn't mention what types of surgeries but I'm guessing that he may need to lay down or have sensitive areas that may need more space than an umbrella stroller. The Peg isn't cheap, but they hold their value for resale and are super sturdy...you could also try to find one resale. I also love the P3 for WDW since the sunshade is awesome (comes all the way to the tray when the seat is upright), it has a snack tray for DS, and the fold is like an umbrella stroller so it isn't terribly cumbersome on the busses.
The surgeries will be on his hands. He has webbing in his finger and they can only do one separation at a time. A stroller where he is somewhat more supported and doesn't have to bend forward (like an umbrella) is what I need.