Should we bring a wheelchair for grandparents who don't usually use one?

Yes. Even if they are active at home, the walking distance in Orlando parks easily hits 7-10 miles per day. A rental wheelchair makes the difference between enjoying the day and spending it in pain.

How do we handle different interests?

Split up. If the grandparents want to see a show and the kids want to ride a coaster, meet for lunch. You don't have to be attached at the hip for the entire trip.

How to plan an Orlando vacation that works for grandparents and kids

Prioritize a pace that includes mandatory midday breaks at your accommodation to avoid meltdowns and physical exhaustion. Limit park visits to no more than two consecutive days and balance high-energy theme parks with low-stress resort or pool time.

Choose the right base. Select a villa or condo with a full kitchen and separate bedrooms. Access to a living room is non-negotiable for grandparents who may want to rest while the kids watch TV or play.
Set a two-park limit. Do not attempt to do every theme park. Pick two core parks for the trip and fill the remaining days with activities like Disney Springs, hotel pool time, or a quiet day at a nearby natural spring.
Use Genie+ or equivalent services. The cost is worth it to reduce standing in 90-minute lines. Grandparents will find physical queues exhausting, and kids will lose patience quickly.
Master the midday retreat. Leave the park by 1:00 PM every day. Go back to the hotel for a nap or a swim. Return to the park at 5:00 PM for dinner and evening shows when the sun is down and the temperature is cooler.

Should we bring a wheelchair for grandparents who don't usually use one?: Yes. Even if they are active at home, the walking distance in Orlando parks easily hits 7-10 miles per day. A rental wheelchair makes the difference between enjoying the day and spending it in pain.
How do we handle different interests?: Split up. If the grandparents want to see a show and the kids want to ride a coaster, meet for lunch. You don't have to be attached at the hip for the entire trip.