I'd like to see an even bigger than Huge Random Map, as that's what I usually play in SP, that would be Humongous or something like that. Like 50-100% more planets than huge maps.
It would also be nice to have a custom random map with sliders for:
number of systems
number of planets
hospitality (affects odds of colonizable vs. non colonizable gravwells)
phase lanes (affects scarcity of phase lanes on each gravwell)
wormholes (affects chance of wormholes, possible to disable them)
resources (affects probability of resource asteroids)