Cody, Wyoming offers something for the whole family and gives you quick access to the South fork of the Shoshone, Clarks Fork, & several to the east. North Fork Anglers is right in Cody and is a class outfit. I would definitely recommend a guided trip planned in the early part of the trip. You will learn a lot. West Yellowstone offers lots of water to choose from: The Madison, Fire Hole, Gibbons, etc....Blue Ribbon Flies (in West Yellowstone) is another class outfit and they cover water from one end of Yellowstone to the other. South of Yellowstone all the way to Jackson Hole: the Snake River, Gros Ventre, etc...there are several guides in and around Jackson to choose from. Any decent 9' 5 wt. fly rod will get the job done out west, but wind is a factor out there. If you go towards the end of August, you will most likely be slinging hoppers and droppers...so gear up accordingly. Lots of water to consider, I would recommend picking an area with access to plenty of water and spend my time fishing instead of driving. Securing a guide will help with the learning curve and may benefit you for the remainder of your trip. In any event, spend some money at the local fly shops and ask questions...you'll be glad you did.