Golden is the place to go for beginners. A number drops to get some adrenaline going, lots of places to practice eddyhopping, squirts, rolling, etc. Most places are easily self-rescuable if you swim, and there are pretty much always people there. Plus, if there's a good chance you'll be swimming, I would personally try to avoid the Confluence and Union because of water quality.
"The world would be a better place if everyone kayaked."-Brad Ludden (Valhalla)
"You only get one chance to run a drop blind."-DD