Nemesis is definetely the best coaster for making use of the land. Even though its terrain is man-made, they also had to keep the coaster height low because of strict airplane laws. Even with the height restriction that would prevent them from making a big first drop that is usually included in today's coasters, they managed to make a famous coaster out of it.
Also the Beast at PKI. I don't think I need to say too much there...