Since I don't like to tune my strings more than one step north or south of home base, I keep instruments set-up for specific home base tunings. For example, from the home base DAA (1-5-5), I'll re-tune to EAA (1-4-4) for the key of A or DGG (1-4-4) for the key of G.
-Prussia Valley Music Box is tuned ddd. You'll often hear this unison tuning referred to as Galax tuning. With the 6.5 fret on this instrument, in this tuning one can play out of D and G without re-tuning. And to get a more haunting sound, I'll use a false nut under the drone strings at the first fret to raise the drones to E.
-Rod Hensley hourglass is tuned Ddd. You'll often hear this 1-8-8 tuning referred to as Bagpipe tuning. This instrument also has a 6.5 fret so one can play out of D and G without re-tuning. As with the PVMB, I'll use a false nut under the drone strings at the first fret to raise the drones to Ee.
-And the other 5 dulcimers, 4 of which are purely diatonic (no "extra frets"), are set-up for some 1-5-5 home base tuning.