I only want to spike the top of my head, so what should I do with the sides and back? Should I shave it shorter than the top or just let it grow?
I think you are on the wrong board. Reguardless, do what you wish with your hair. Maybe even consider growing it long...
... we speak no such language. 'round here, we speak longhair! Wado!
As one who appreciates contrast, tall spikes with the rest shaved gets my vote. On the unstiffened days length hanging down over the short looks great too. If you think you ever want to have a short section, now is the time to do it rather than growing it all and cutting some back later. Once you have the length it may be hard to give up. Also be aware, having some section long might tempt you to grow it all to see how it looks. All interesting possibilities.
Elizabeth
grow a mullet bro, the ladies love them.
that's business in the front and party in the back.