Thank you very much. That answered a lot of my questions. However, I am still unclear on one thing. If Mom and Dad both have ECVs, can they board the same bus? I know AKL is far away from some of the parks; is it going to be too difficult to take the bus everywhere with ECVs?
Too is something that is very personal. Some people will have a rant whenever they don't get on a bus within 5 minutes, other are happy enough to wait longer. With 2
ECV's you are complicating it a bit as in needing 2 available tie down spots on the bus. Most busses still only have 2 spots (allthough more busses with 3 or even 4 spots are popping up), so you can see the next thing coming; risk of there only being one spot available. It's a realistic risk, made higher if travelling at high peak times of the day, factored in with time of year etc. etc. Also at AKL you are the 2nd stop as the bus loads at AKV Kidani first and then pulls upto AKL. So; some risk of somebody being already on the bus.
Easiest in those cases; one takes the spot available and the other waits for another bus. This is a better odd than not taking the one spot and continue waiting for 2 available spots. Meet up again before entering the park. Either use phones to keep in contact or agree up front about meeting spots when needing to split up.
In 2009 -sjeez, time goes by fast!- I did a 8-nighter at AKL with a friend of mine. She's a manual chair user, I'm a powerchair user. My next door neighbour happened to be an older man using an ECV. We somehow happened to have the same timing during that week. He was the biggest reason if we had to split up, basically.

Having said that, we travelled during low attendance (late sept) and not at peak travel moments. Think we had about an 80% rate that we could get on the same bus and back then no 3spot-bus to be spotted yet. Maybe once where splitting up would result in the 2nd traveller not getting onto the next bus to that destination because of all it's spots being used already. Meeting up was easily enough, no biggie.
Just something you keep in mind when travelling with 2 mobility aids, IMHO.
Another option to consider; renting one ECV ofsite and one in the parks. Downside; needing to be in the park before all ECV's are rented out, which can be a pain in peaktimes. Perk; only one ECV and thus only one tie down spot needed. Parents can alternate between using the ECV for the distance to the rental. If having a room close to the lobby, the busstop is really close at AKL.
Would it be easier to stay on the monorail? Should we rent a car and drive to MK with the ECVs?
To each their own taste and opinion, but IMHO it is not a must to fork over a lot more $$ just for the monorail. Even more so now that the operating hours are so poorly. Sure, it's easier to get onto and can transportate more mobility aids, but only to 2 parks. It will still leave you with busses for the rest. And unless staying at Poly and walking to the TTC, going to Epcot requires a transfer which reduces the ease.
Location of resorts that make much more impact IMHO is staying at one of the resorts that are within walking distance from Epcot and DHS, like the YC, BC, BW etc. Walking/riding over to both parks would eliminate bus to those two. Not worth the $$ when not spending a lot of time in those parks though, IMHO.
Rent a car? Again, to each their taste but IMHO not a must to spent all the $$ just because of needing a mobility aid. If you want a guaranteed being back at the room within 20 minutes after leaving a park no matter what; sure. But if not being too unreasonable with expectations the busses aren't that bad.
For people like my parents who are arthritic and can't walk long distances, are ECVs the ideal or would electric wheelchairs be easier to maneuver? Once again, many thanks.
I would doubt you being able to find a renter that would be OK with renting out a powerchair to either of your parents if they are not regular powerchair users at home. Operating a powerchair is straining and a lot more difficult than operating an ECV. ECV's can be nerve wrecking enough for the elderly, using a powerchair in a situation like WDW with the crowds and narrow areas when not used to using such an aid would be hellish for most probably, let alone when being elderly. This results in one last thing; if not already done, have them try out using an ECV at home. This way either they get familiar with the basics of operating one (each will have their own caracter, but still) and get some usage under the belt before having to go out into big crowds and operating narrow spaces. This will leave room in case one isn't safe or doesn't feel safe/confident enough to operate one to get to a plan B (which would most likely be wheelchair or rollator usage).
Same goes for you if there is any risk of you having to be the one to navigate the ECV's onto the bus. With 2 of them, at least one will have to be tied down in a lesser easily navigated spot. At best the spot in front of the spot right across the back door, in the worst situation; the spot right in front of the back door on the side of the back door. This can take quite some navigating. A breeze when used to it, but can become a sweat-devil if not used and having gotten into a wrotten space -read; more difficult to get out, now being nervous and wanting to hurry resulting more quickly in flustered moving-. Many elderly need some assistance from their loved ones getting the ECV onto the bus. So; you'ld better also practice using it and if need be; parallel parking.
