I may have to play with that. My initial thinking was to leave it blank so that users could fill in the place they may be heading to. I tried to make it as easy as possible to type too with autocomplete of US cities and states. Also, the geolocation is pretty awesome on a smartphone. Is geo-ip very reliable on phones?

Edit: I'm making the geo-location button add zipcode as well to get a more accurate answer.

I love the feedback. Maybe I should add a feature suggestion box to the site itself. Thank you.