Yellowstone. wadable rivers all around you. The Madison and Gibbon are all easily fished with roadside access and sept. is a great month to be there. Lots of things to do with the family as well. I like to stay in west yellowstone for the hotels, restaurants, fly shops, Imax and walk around small town shopping. Easy drive down from Bozeman airport.
You only need a guide if your doing a float trip outside of the park.