I'd say keep the wonders! They are cool and really add to the fun of the game. It doesn't matter to me that they are unrealistic (well, most of them are, some aren't tho), you can never obtain complete historic realism with this game anyway, so can't you just leave this feature in??? If you really don't want to leave them, at least go with the option of putting them inside the city!

but i can't vote yet... :S