My experience with Grado SR60s has been that they're very comfortable once (a) you've bent the headband for best fit, and (b) the ear pads are broken in. The SR80 has the "bowl" style pads, which I have no experience with; the SR80i (I think) has the SR60-style pads.
I also have a set of Beyerdynamic DT 770 Pro/80s as well. I usually use the SR60s with my portable player or my laptop because they're far easier to drive, while the Beyers are plugged into my E-MU 0404 USB for desktop use.
I'd recommend either set of 'phones. The Grados' strength is midrange, while the Beyers have very strong bass when you need it. If you need isolation, the Grados are not for you, since they're completely open to outside sound and also let anyone next to you hear what you're playing.
Both need some break-in to reach their full potential, but not a ridiculous amount.