DADAC#E - Usually use this for twinkly/jazzy mathrock with lots of noodly & tappy riffs & post hardcore
AEAEFF# - great for plebeian grandstand-esque & mathgrind style riffing (being able to bar the 3 highest strings to make a dissonant chord makes it incredibly easy to do those daughters style riffs and danza-ish tappy parts)
AEAEG#B - like the first tuning, but lower. Using this to write some "epic" blackened hardcore. Good for sludgy caveman riffs, but also allows for lots of pretty chords and postrock-y melodies.
Tfw playing math rock ruined you as a musician so now you have a hard time playing in "normal" tunings, but dammit are you good at wacky time signatures.
Nothing special. Pretty much standard tunings across the board, mainly because I just don't seem to enjoy how chords feel (or sound) when I play in drop tuning.
6-string: D-standard (the true home of death metal)
7-string: E-standard + low B
8-string: Eb-standard + low Bb & low F
And as far as string gauge I try to go as thick as I can for the higher tension, I prefer that feel on the strings when it comes to playing chords and the more techy side of music.
So far only E standard and Eb standard. If i had more guitars i would have shit tons of tunings.
I plan on getting a 7 string for my 5 year anniversary over a year away soon. Plan 9n having the tuning be G# C# F# B E G# C# so i can play some cannibal corpse.
I also am gonna be having other guitars that go from as low a tuning as that up to E and everythin i between drop tunings. I will probably have 1 floyd guitar for every standard tuning and a hardtail in every tuning and if i need to go to a drop tuning all i have to do is downtune that string
From top to bottom:
7-string: EBGDAEB
8-string: EBGDAEBE
Very imaginative, I know. They're my main instruments, the 7 has a floating bridge and the 8 has a fixed bridge. So they stay in the same standard tuning since I use them for everything.
I used to tune my 8-string to EBGDAEAC# at times, but the songs I was writing in that tuning were harder to play with the dropped A, so I tuned that up to B, and the scale length wasn't suited to C#, so I went back to E. Now I just play those songs with a capo on the first fret on the highest seven strings.
My classical 8-string is DAFCGDGD. So down a whole step, but the lowest two strings dropped. I wanted to play 'Para Mexer' but I liked the darker sound so much I never tuned it back up.
My 7-string electric violin is EADGCFBb. So it's tuned in fifths, but with that low Bb and F I can bow out some Meshuggah.
In a previous metalcore / death / prog metal band I played mostly Drop C with one song in D standard. Nowadays I am mostly writing in either Drop C on a 6, a half step down on a 7 (A# standard), or C / Drop A# on a baritone.
That said, the main reason for my having too many guitars is that I like variety, so I have guitars set up to standard (E / Eb / D). My 8 string is set to standard because anything lower feels too damn floppy (hell even standard feels too damn floppy at 26.5" to me).
When I was younger it was all standard, a half step down, and drop D baby, because I started playing in the 90's.