That is not all contradictory... the only parts that contradict each other a bit is that you want something nimble and that handles well but still has a lot of storage? =P It'll store plenty of groceries... if you wear a backpack. *hides smile*
But I took my first ride on my motorcycle today! It was fun. I can't wait till I can do it in a fully legal fashion (my non-paper license has not arrived in the mail yet).
In terms of mileage, if you get one of the smaller bikes (i.e. 250cc) the mileage is guaranteed to be fantastic (~65-70 mpg). Even the 600cc+ ones are still good... one really doesn't need more than that to start out with. (Apologies Pink, I know this is slightly off-topic. Just had to share.)