I've added a utility to my website that plots a 3km honey bee forage
zone around an apiary site.
Interesting to see what your honey bees are potentially using for
foraging.
It's free, based on google maps; you are more than welcome to add your
apiary sites to try it out.
Dean
Have you seen the NASA honey bee forage map?
http://honeybeenet.gsfc.nasa.gov/Honeybees/Forage_info.htm
What a great idea.
I used a ADC street map in plotting my yards out when setting a breeding program. The area maps are large enough with detail that 5-1/4 inch made a 2 mile circle. It not only allowed me to concentrate on finding farms within a certain distance, but kept the distance in an area good for drone yards and genetic saturation.