I've played D-A-d-d 99% of the time for the last 35 years, but I also like D-A-c#-d for some of the interesting chords it offers as well as the chromatics.
Tom Fellenbaum builds some great instruments, too. If you like Celtic music, he alternates Sundays with Richard Beard, another great dulcimer builder, as a host of Celtic Roots on WNCW from Noon-3pm Eastern. Richard was on today, so Tom ought to be the host next week. (Available online.)