I learned to sail on Lake Dillon with a Cal 20. That was 7 years ago. Now we sail an O'day 35 on Lake Superior and I'll repeat what I was told by other Lake Dillon sailors, "If you can learn to sail on this lake, you can sail just about anywhere!" This lake can change its mood quick. I was caught out in the worst squall I've personally ever experienced. The mountains funnel wild winds but it sure is a beautiful place to be out in a boat and I'd have no hesitation to go out again.
The regatta mentioned previously is a big deal, lots of boats and good sailors and fun to watch from out the water.
The marinas are few, only two and I don't recall there being much transient dockage, at least at the Lake Dillon Marina, Perhaps there is more in the Frisco marina but beware that the year after I left Summit County, the lake level was so low that the Frisco marina was high and dry.
You can't anchor in the lake, It's far too deep and the shore drops off very quickly.
Hope this helps.