I recently had a business trip to Salt Lake and took the opportunity to go stand in the Weber for a little bit. I've fished the Provo and Green and I think that I like the Weber the best!
I spent most of the weekend in the middle portion just north of Park City. Although the caddis were incredibly dense, I had no luck on using any my dry flies during the day, but at night, that was a different story. During the day, I used hare's ears and pheasant tail with incredible success. Although I would say about half of my catch were white fish, the 24" + browns were a welcome change. As the sun went down, the trout came up. In some areas it looked like boiling water and the fishing was great. Despite all of the caddis in the air, a #12 brown grasshopper proved to be the most valuable.
I know that most will still head out to the Provo, but if you haven't, I highly recommend giving the Weber a chance.
All the best....