I know what you mean about finding places without a tower of trees surrounding it. I was kiting around our highschool, since it has a good north-south corridor - no large trees for 1/4 mile. But for east winds I had to get out and look around.
If I didn't mind the holes in the sale, the wheat field would be an option - hay, didn't I hear about a kit where the maker put hundreds of holes in for venting?
I did find the grass parking lot at the county fair property, could use it when it is open and we have a county park where there are few trees leading up to the beach. Good for East to west winds and has soybeans across the road so there not much to stop the wind. the down side is that it slopes down to the lake and the width is limited to the grass between parking lots 120 feet or so.
I had comtemplated using the parking lots at our high school, since they are 400 to 500 feet long - on all but the strong wind days, they should offer some good air to fly in. But I don't want to scrap up the kite.