Hiya, Alison, and welcome to BYC!! I graduated H.S. from Staples, MN. Dad and a couple of sisters still live over that way, though I'm in WI. We just have silkies and there is variety within them, but if I didn't, I'd do what you're doing and probably have about six different kinds at least.
Welcome. My advice, the bigger the better as long as it is secure. 1/2 inch hardware cloth is your best friend. Make an apron to prevent digging predators from getting in.
Welcome Alison. My RIR was a great layer for me. My leghorns are the friendliest girls I have and great layers of large-jumbo white eggs, problem is frostbite on their combs!
I'm limited in space so I've stayed away from the big Barnvelders. I have a friend who loves them. I've always wanted barred rocks. Lots of folks here have at least one in their flock. You will have a pretty egg basket.