my Marathon RR and Warlock NJ are tuned to D (everything whole step down, I kinda hate drop-tunings so I always use a lower "standard-tuning") but those hardly get used at the moment, I may change their tuning somewhen, but no need for it now.
the Ibanez 7-string (that I play nearly exclusively these days) is in standard tuning. didnt feel the need to go any lower than B so far