I play the 8 string resonator with a lower than usual action, especially considering that I use it for some bottleneck slide. The lower action means I can get a dirtier sound with the string slapping, against the frets/fretboard when I play. The string spacing / nut width specs are very similar to a 12 string guitar with the nut width being approx 50mm.
Currently my tunings are:
Main open A tuning from low to high
A E A E A C# e/e
This changes very easily to standard tuning with a low A bass string
A E A D G B e/e
From the main open A tuning I can also very easily get to what I think the most practical tunoing for the general public - Open D tuning with a low A (this is how I played Jeff Martin's 7 string), low to high
A D A D F# A d/d