757s are the best plane I've operated. They costs about the same rpk as the 737 (400 and NG) but carry up to 50% more seats, so you save on route fees etc. Plus, their leases is around the same as a new 738/739.
They're a great plane. I love them, they're great for domestic, hi LF routes, plus have the range and seats for good, middle distance, like your Hawaii or US to Europe with a decent pax load. Plus you don't have the high costs (staff, leases etc) of a big widebody (A332/762). You might find them a little small on some routes, but you're better off having a full small plane than an empty big one.