Hello Taylor and thank you for bringing such an important question to the Disney Parks Moms Panel.
Being somewhat Pooh Bear sized myself I quite understand the concerns for your dear husband, so please let me reassure you that pretty much every size and shape is well catered for at Walt Disney World Resort!
In my own experience I haven't yet come across an attraction that I could neither enjoy or experience with my family because of my size.
Did you know that many attractions at Walt Disney World Resort are equipped with bench seats? For example
Pirates of the Caribbean or
Living with the Land and if needs be you could politely request that Cast Members seat your family accordingly so you are not all squished in together.
My general advice would be if you are at all concerned about any attraction seating, speak with the Cast Member hosting who will be glad to help make your experience as magical as possible.
You may wish to perform a simple Google search for
'larger sized WDW Guests' which does find some helpful and reassuring articles.
If I can sprinkle any extra pixie dust onto your upcoming Walt Disney World Resort vacation please pop back to ask me another question.
Have a great Disney day.
~ Jane