Dominions has map locations that give bonus to spells cast from that location. I think it works very well. It would work even better in a game where you could NOT build a city or fortifacation on that location. It would make it a harder choice to decided if you want to risk your avatar or spell casting hero by putting him on that spot to get the bonus.
I'm not a fan of locations that;
allow the casting of a spell not castable anywhere else
allow you create items with a special power you can't get anywhere else
As with everything I think it is a matter of ballance. Random is good when it is somewhat ballanced and can be overcome with skill, knowledge, and tactics.