The east of Colony 9 is good for Lv. 70-75 enemies. From Lv. 76-80, the platforms on Raguel Lake on Bionis' Leg have a lot of enemies on them. From Lv. 81-5, there's a few enemies at the southeast of Satorl Marsh that are useful for grinding. From Lv. 86-90, explore around Eryth Sea and Alcamoth. Hope this helps!