Moon, Sky, and Lufaise Meadows were the best places to exp prior to the expansion. You can also go to the bottom of Kuftal tunnel and fast chain tigers (closing chains with Ladons for some extra exp).
That said, even w/o the exp bonus, the expansion zones are far better. Imps/Flies/Colibri/Mamool Ja give as much exp as weapons in Moon or Sky but they die *much* faster.
For Lufaise Meadows you need to have a party geared towards killing ITs rather than VTs. Use PLD tank for birds or NIN tank if you are taking rams. For birds, you need a WHM for Cure V and piercing damage helps. IMO, the best setup for taking them out would be PLD (with Joyeuse for piercing), 2x DD (RNG or DRG), RDM, BLM, WHM.