Peter T. said, "Open tunings are far more user friendly for beginners." But what's logical isn't always what's practical. I think one thing that makes standard tuning easier to learn is precisely that it is standard - the books and people that you consult when you're a beginner assume standard tuning. When I started on guitar I got my basic chord vocabulary from asking and observing my friends, none of whom ever used alternate tunings.

JohninKansas said, "Food for thought: is it the selection of doubles available on open strings that makes a certain few keys "fiddlers favorites?"

My theory is that there's two more reasons why D,G, and A are easiest on the fiddle:

1. All the open strings appear in these keys (except the open G string in A, but you don't need the G string nearly as much as the others), which makes not only the double stops but also the fast melodies easier.

2. None of these keys have notes that are a semitone above the nut (no Ab, Eb, Bb, or F). So your index finger is always a full tone above the nut, and it's easier to play in tune if that first position is stable.

Marion