What you have described seems possible technically, but implementing it might be tricky. You would need to come up with a way to determine what the area you can deliver to by ground is, then determine if the user is within that area. There is no tie in for a map for any portion of eCart.
Perhaps there is a short list of zip codes that should have ground shipping available. You could check the shipping zip code that is submitted on the checkout page and if it is in the list you can set a session variable. This session variable could be the service type that you use in your shipping quote server behavior. If the zip is in the list set it to the ground option, if the zip is not in the list then set it to the 2nd day air option.
If you have any further questions about this type of setup or any specific questions about accomplishing any part of this let us know and we will help with whatever we can.
