Gore Creek runs through the town of Vail. I've caught decent rainbows right in the middle of town--with all the tourists gawking at me. However, downstream of Vail Village the stream is considered Gold Medal water (Colorado's equivalent of a Blue Ribbon stream). This stretch goes all the way to the confluence of the Eagle River.
North of I-70 along US-24 there is good access to the Eagle. Look for the town of Minturn on a map. It also fishes pretty well along I-70 all the way through Avon. Here is some more info: http://flyfisherman.com/rmwest/rpeagle/
Some of the guides in the area can also take you to the Colorado River, but it would take more time and effort to do this. If you want to drive even farther, you could head west on I-70 though Glenwood Canyon to Glenwood Springs and fish the Roaring Fork.
Having never utilized the services of a professional guide, I can't give you much advice in that regard. There are several fly shops and guides/outfitters in the valley.
Hope this helps. Have a great trip!
