Surely your toddler won't be so accident prone by summer time, right?
I'm not understanding the logic of ruling out the beach.

Massanutten (childrens museum in harrisonburg) and Dutch wonderland/Hershey park are all encompassing for wide age range.

My kids loved Acadia when they were young.

If they are not so small you can easily try Greece. I was on my vacation there and it was a wonderful time. We used to take a taxi from Thessaloniki https://www.hellenictaxi.com/ and traveled that beautiful peninsula. I am sure that it would be comfortable travel with kids.

What about hiking? Would your little one go in a backpack carrier? We did Portland/Cannon Beach when our oldest was 22 months and it was great. Cool city and things to do, with hiking, I would think older kids would love it too.

I have a 14m old toddler (almost walking) and 2 Very active boys ages 7 and 9.

Can you recommend vacation ideas where all kids can have a good time?

Looking for summer vacation and winter break ideas. Can drive or fly.

Toddler hates sand. She is accident prone since she is a beginner walker. She needs play areas designated for young children.

We have recently gone on a cruise, went to Disney world when toddler was a baby and a few beach weekends when she was an immobile weekend. DH and I would take turns staying in room with baby or stroller walks while other parent would take older kids to the beach.