We did a 12-person multi-generational trip a few years ago that included 2 sets of grandparents. I was the one in charge. Glad we did it but also glad it was a one-time thing!
(I kid, I kid... kind of)
2 of the grandparents rented scooters from an off-site service to have on hand whenever needed, 1 should have but refused and would only get one at the park (and even then we basically had to force him). He had the hardest time of all with the distances so I began to dread each travel leg coming and going from the parks, if I'm honest. We were staying at Poly and getting to Epcot, for example, requires SO many steps and ramps before you ever get to the
scooter rental. Combined with the July heat it was a lot for this individual. We all made it, but it wasn't without stress. Gave me a new appreciation for those with mobility challenges when traversing a property as vast at WDW.
If doing that trip again, I would rent enough scooters off-site for those that need them just to have on hand - if they feel like they need it, great - if not, get one at the front of the park. More $, yes, but I wish we had had the optionality at the time. A 10-day trip is long and spirits/mood/physical abilities may shift around day to day.
Not sure when you say "Suite" if you're thinking a hotel-side suite or 2 or 3 BR DVC villa. I've stayed in many of the hotel-side suites so happy to comment on them if helpful. WL only has one hotel-side suite (have not stayed there, it's hard to book!), I'm not sure off the top of my head if it holds 8.
FWIW on our multi-generational trip we were in a few suites at Poly. There are pros/cons with every resort but it worked well for us. That said, when reading your original post I was left thinking WL sounds like a solid choice for your family given your description.
Good luck with the planning! Despite my maybe slightly negative tone above, we all still speak fondly of the trip and it created a lifetime of memories for multiple generations.