Mark, Dusty's option of using a capo is quite viable. I use one myself, sometimes. However, depending on what's being played, I'd rather retune. I read an interview in DPN with Alan Freeman where he said something to the effect that we're already "missing" frets so why would you want to shorten the fingerboard with a capo and make more frets unusable? Even tho' I was using a capo a lot at the time, that thought stuck with me. I'm trying to play a lot of tunes/songs in the correct key without using a capo and staying (like Dusty) in DAd tuning. [To reiterate what he said, the lower case d just means it's an octave above the bass D.] I play Down Yonder and Silver Bells (not the Christmas one, the Mexican Polka) in G and You'll Never Leave Harlan Alive in A without either retuning or using a capo. If'n I'm just going to be chording, playing rhythm, like Dusty (again,) I play barre chords without using a capo or retuning for G and A tunes.
I usually take (at least) 2 instruments to jams: 1 tuned DAd, 1 tuned DAA, both of them 3 courses. The DAd I can tune to G DGd, A minor EAd, D minor DAc and the DAA I can tune to A major EAA or D minor DAG all with moving only one string. If I take a 3rd instrument, it will be tuned to G, either a Jim Good in his special G tuning or a small 4 string Paul Pyle tuned GDDg.
You see, you've got options. That's something that makes this instrument really cool and also really frustrating (as in capo or retune or another instrument, yeah that's the one!) at the same time. Those folks that like things really cut and dry can have a problem getting their heads around such things. LOL. Well, I've probably confused you enough for now. Keep picking