Hi Kathy,
I say go for it. It sounds like you have a wonderful husband who cares about you a lot. Yes it may tire you out for a few days afterword, but think of the wonderful memories you 2 will create. If needed take along a wheelchair or rent one at the museum, this way you will not have to walk as much. It is easy for us to get into our comfort zones. I try to challenge myself every chance I get. You will be surprised at what you can accomplish.
Been There Done That. Challenge Yourself
Best Wishes
Hank