17s don't suck. They are nice.
1.3lb/in on mine, nobody around here will agree they are nice though - it's a personal thing. If you want the extra 2 in. be prepared to make the sacrafice in acceleration. You can always just build your car to handle the wheel size, if 17s on the street are important to you. Track day they are a waste, unless your looking to pimp bitches in the pit. For the street they are justifiable for the increased curb appeal, or just the fact that you like your car better with them. Always remember whose car it is.