I went to Iceland back in 2010, GREAT PLACE!
8x10 and 35mm were my formats of choice when I went(8x10 for "serious" work, 35mm more as a walkaround camera). I found that I used my longer lenses most of the time(on both formats).
IIWY, I'd bring the 80mm(if you have one) as a normal FL, and a longer lens(250mm would be my choice). This is for me and MY vision however. We're all different and how we see "photographically".

****I'd also make sure to bring a 2nd body and (at least) a 2nd film back as backups, it's cheap insurance and not THAT expensive.****