Plane Trek, Part II - Tropes

So yesterday I posted about Plane Trek. I missed a few tropes, though:

• Space is an Ocean: It's almost a no-brainer. Most sci-fi stories use it, and while I haven't read Spelljammer, I've seen some ships, and they look more ship-like than spacecraft-like. (Most wouldn't float in water either, but they have sails.)
  
• 2D Space: Makes for easy mapping, if nothing else. I think the Astral Sea should be a few miles "thick", though, to allow for 3D maneuvering in ship battles without the hassle of mapping a spherical Astral Sea.
  
• Home Is Kinda Nice: The Federation in Trek is a pretty decent place to live. Adventure is out there, on the Final Frontier.
  (I couldn't find a TvTrope on the subject. Home usually sucks in fiction, after all.)