What are the best places to gain experience in Pokemon Diamond and Pearl?

Hey, I'm looking to train up my Pokemon and was wondering where the best places to find experience are in Diamond/Pearl? I don't mean EV training, I mean just plain experience points for leveling up. Is the Elite Four still the place to train? I found that Mt. Stark is great for Water, Grass, Ground types and the ocean near the Fight Area is great for Electric types (Especially against the one trainer with the Lapras), but after I level up after 70, I find it harder and harder to find decent experience points.|||From a Chansey, thief a Lucky Egg or something from a wild Chansey. It raises 50% experience and stuff, you can use Exp. Share too. Good spots are the Elite Four and in the Island in the back. Vs. Seeker helps definitely.|||The elite four and the Survival area is good also.|||elite 4 ,I trained a lv.90 kingdra to lv100 after less than 10 challenges against the whole elite 4|||elite four|||those are the places i use. other than that, the elite four, sorry pal