Sorry I can't advise on streams, etc. but I have been to the Museum of Fly Fishing. Being a fly fisherman, I found the museum well worth the visit. As to whether a non-fly fisher would like the visit, I would say yes, but then I enjoy visiting museums in general. If worse comes to worse, they could visit the Orvis store next door or take a stroll around town while you check out the museum.

Regards