And "ground-friendly" means making locations, that:
1) Has direct safe roads
2) Large enough quest zones to have enough mobs/items for all players
3) Several routes to approach this zones
3) Lower density of mobs, so 100500 mobs don't constantly aggro, while you fighting with other mobs
4) Lower respawn rate, so mobs don't respawn on the top of you head
5) No elites/fat mobs/large mob packs, that have to be avoided
6) No artificial obstacles, like 1m high ridges, you can't climb back, if you fall from, and have to ride around half of location instead
7) Etc.