I was never much of a flat-picker on guitar until I started playing in open tunings. Yes, it breaks all the conventions to play "Ragtime Annie" or "Cuckoo's Nest" in open C tuning capoed up two frets, but it works for me, other pickers tell me it sounds cool, and I've never been much on convention anyway.

Many self-taught rustic fiddlers play in "cross-tuned" tunings like ADAD (for D tunes) or AEAE (for A tunes). It might be worth playing around with.