Not going to judge any choice here - whatever gets the OP and his wife out and about is a winner. On the trailer front though, having recently added one to my arsenal, it would be hard to overstate how much of a difference it makes in needed effort. The weight of a trike is already an issue for climbing. I would think that a 25 lb. trailer with a 25 lb. grandkid would pretty much bring the parade to a standstill. I'm sure a flat 5 mile jaunt to the park would be fine.