Not sure if this is useful to add, but yes I’ve always just hand-waved the exact altitudes. When playing Star Wars with WEG, originally, I mentally put all flying/floating vehicles into Landspeeder, Airspeeder, and Orbital categories. I also explained the differences in altitudes that could be reached by the relative power of their anti-grav modules to the size of the vehicle. As a vehicle moves from ground contact, the range to the surface gravity of the world created a need for a stronger powered antigrav module (the strength of gravity between two objects is relative to size and distance, thus the strength of antigrav would need to be greater as the distance to the gravity producing object increased, was more handwaved reasoning).
Orbital was for shuttles, an Xwing, starships, etc. Anything that could fly to any altitude and reach orbit. These vehicles could even hover near orbit with the antigrav modules which were strong enough at that range. Once in orbit, antigrav was only useful for keeping occupants on the floor, revert to subspace engines/thrusters.
Landspeeder’s antigrav was only strong enough to allow the vehicle to float. This could be used for floating robots (not flying ones) and hovercarts such as Han’s carbon-freeze trip at Cloud City.
Airspeeders could not reach orbit. They could fly, but their antigrav was only good enough to fly over mountains, tall buildings, etc. I didn’t want a Hoth airspeeder to be able to fly to orbit.
The rare, archaic purely thruster-powered vehicle (no antigrav) of course would need vastly more power to fly than a vehicle that could negate its own gravity.
