Spelljammer 4th Edition
Deities and Domains
Entering the Domains
The orientation of the astral flotsam that gives the astral sea its name also is the orientation of the actual watery seas of the gods’ domains as well, (with the Nine Hells being an exception.) Entry along the astral horizon typically bleeds into the sea of the gods domain.
I think for staring we will be using the Forgotten Realms version of the cosmos, as far as what domains are available to travel to.
That is not to say the realms listed in the Planes Above and Manual of the Planes don’t all exist. Unless you want to make it a bucket list kind of thing, Odds are you guys wont see EVERY SINGLE DOMAIN. But there are enough out there as well as isolated islands, motes, and ancient planes that it makes the perfect setting to put nearly any adventure in. Combine that with the Elemental Chaos, Shadowfell, the Material Plane, The Feywild, The Abyss, and dozens of other places and more importantly the speed and somewhat ease of ability to GET THERE; you have this setting of utter flexibility, which is what we are shooting for.