Welcome to disABILITIES.
I agree with the other poster that AK is sort of hilly, but mostly gentle hills. The walkways are "themed" as dirt paths in some cases and can be bumpy and uneven. I don't know much about Universal, but I can give info about the WDW parks.
First, the
monorails. If you get on or off at any of the MK resorts (CR, GF, Poly), you are at second floor level and will be going straight on or off. When you get on or off at MK, TTC or Epcot, the monorail station is at second floor (or higher) level and there is a long, steep ramp to get there. I have heard there is an elevator at Epcot, but I've never seen it. Ask a CM about it.
At
Epcot, here are the hills I can think of:
The Land has a long, steep ramp to get up to the building. Once you are inside the building, there is a ramp that goes down about 1 to 1 1/2 floor to the Garden Grill restaurant area (directly across an open balcony from the entrance), the Circle of Life movie (to your right when you come in) and the elevators to get to the lower floor (to the far left of the entrance, just before you pass the restaurant).
The Wonders of Life Pavilion has a smaller ramp to go up to the building. Once you are inside, there is a ramp to get down to the floor of the building.
In WS, Canada and Mexico appear to have only steps to get up to the pavilions, but there are hidden ramps to get where ever you need to go.
In WS, there is a sort of bridge area that connects the UK area and France. This is a long, fairly steep hill that goes down from France into the UK. One ride that comes to mind is American Adventure. The theater for the show is at 2nd floor level. The hall you enter the theater from (when the CM opens the doors) has 2 flights of stairs - one on each side of an escalator. So, stay to the center to take the escalator. If you have a wheelchair,
ecv or would rather not use the escalator, there is a small elevator just to the right of the doors you enter the main room from. Sometimes when it is busy or close to show time, CMs forget to show people to the elevators (we've seen people is line for the staris and sent them to the elevator).
At
MK, fantasyland is higher than the other "lands". To get there from the area in front of the castle, there is a ramp (fairly gentle, but still a ways up). There isn't much of a difference between Fantasyland and Tomorrowland, but there is a fairly steep hill between Fantasyland and Liberty Square. Other than those, it's fairly level or gentle hills.
The
Studio doesn't really have anything that comes to my mind.