Farms seem to be the obvious choice - lots of plants, open land for the bees, increased crops for the farmers etc. My search took me to 2 farms, where they both agreed that I could keep bees there. Unfortunately by the time I pulled my finger out, some 2 years later, I would have needed to go and approach them again to see if the permission was still there.
I know that one had a swarm on his land, and the beekeeper who went to get the swarm ended up housing them in his hives on that land. I was aware then that this farm location had been taken.
In the end, I asked a local businessman, having used google maps / earth to locate some open areas. This businessman has a great location, with 24 hr security in place that made it perfect.
My other location is an area of land that I wanted to build a house on, but the current owners wanted to do this themselves and planning authorities wouldn't allow it. The land lies unuse. I phoned the current owner who is in France, and he agreed.
The groundwork, the knockbacks are the hard parts, but the necessary evils of finding a good and suitable spot.
Whenever I am out, I am always eyes open for a good spot. I only have one hive, got that yesterday, am new to beekeeping, but have 2 locations with permission and multiple potentials in mind.