I know everybody here always jumps to praise the kilo for it's great value,but since the OP is looking for a commuter i think a conversion is a much better choice.They can often be bought at a reasonable price on craigs list and give a comfortable ride,can be fitted with panniers most have flip flop so the OP can start out SS.It sounds like the OP hasn't ridden in a while and wants to get back into it and i don't think a 7 mile commute is a great way to learn and appreciate fixedgear riding.