Fly Fishing Techniques

I have some guest from out of the country. Who want to go fly-fishing this August in Califorina. Need to know what flyies, rivers and spots are good and bad this time of year. Would like to ONLY fish RIVERS for TROUT with in, 6 HOURS of LA, like the Kern, King and Merced rivers. Also need info on guides, cabins or motels. Thank you.