I looked at getting a nice door armrest pad from LeatherZ, but even the 1" foam block I had been using seemed too thin (I think LeatherZ's are 5/8" total, but they can add some more). Today got a new block of 1 1/2" thick 'crosslink' foam in a 2" by 4" square. Held on by looped painter's tape. Ghetto, but obviously don't want to make this a permanent installation: Went to Toyota last night with a small level and measuring tape. Set new Camry seat shown below to a reasonable fit for me and found the armrest vertical drop to seat bottom (flat, white part, not side bolsters) at about 11 inches. Guess what that same drop is in my Prius? 9 inches. Nothing funny about the adjustment of seat below: 1 click forward from full back, 4 pumps up, seatback reasonable. When this (Prius) door armrest is too far from the norms of most other cars, it 'sticks out like a sore thumb' as they say.
LoL, I won't go to dealer for service with block of foam shown above. They removed it and tossed it out somewhere. I said, ah, not going to try to hunt it down. Went to foam shop and got two free new ones. C'est la vie. I like the foam block, cushy and makes it easier to reach that wheel at 7 or 8 o'clock.