With this thread, I am trying to think inside the box to spice up hyperspace. So what is the box? The main bit is that hyperspace travel is a straight line from A to B. The other bits are speed ups are nice, but slow downs really really suck.
For this vision of hyperspace, I'm going to start by wiping the slate: the huge, arbitrary fields of deep hyperspace are right out.
So, what have we got? Constellations, star systems, and some labels.
I think it would be fun to tie real-space and hyper closer together, so what if nebula constellations have "hyper nebula" terrain around them - hyper because it has no slow-down effect. Pulsar beams could also extend a bit into hyperspace, but only the pushing effect.
I do like how hyperspace storms work, so I want to bring them back somehow. How about some constellations be "XYZ Molecular Cloud", inspired by the Telmun label, and surrounded by molecular cloud terrain. Because hyperspace can be weird, sometimes sections of these clouds experience "antimatter storms", where trace antimatter spontaneously appears and explosively interacts with the cloud. Antimatter storms would function exactly like current hyperspace storms, but molecular clouds would only have a stealthy-when-stationary effect like ring systems.
Taking more inspiration from labels, I want to suggest a couple new constellation types. The first is "Wastes of XYZ" constellations. Wastes are intentionally empty, with no more than one or two stars at the edge of the constellation. The second is rare "XYZ Deeps" constellations. Deeps constellations would be filled with a new "deep hyperspace" terrain that slightly reduces (say 10%) sensors, profile, and maybe speed (larger fleets more) as if your fleet were underwater. It would be awesome if it were shown by applying a wobbly filter like hyperspace's background uses, though less intense.
The edge of the hyperspace map has always bothered me, but combining deeps terrain with the Orion-Perseus Abyss label gives me an idea: abyssal hyperspace - like deep hyper but much worse, say 50% reductions. Surround the entire map with it, maybe label the top side the "Leeward Abyss", and put a ring of deep hyperspace between it and plain hyperspace. That would make the Sector sort of a continent or an archipelago. Give abyssal hyperspace the wobbly filter and a sharp edgeline where it meets deep hyper and it would look like a continental shelf. Could vary up the "coastline" with "XYZ Abyss" and "Gulf of XYZ" constellations that bring the deep and/or abyssal hyperspace in closer to the core.
All these terrains, except abyssal of course, would also appear in random patches and swathes around the map.
While the above terrains add much needed variety, I think there needs to be more small-scale terrain and stuff to break up the monotony.
Take inspiration from pulsars, for example, and have "neutron burst" terrain that lies nearly or totally invisible until a fleet crosses it, then "bursts", shoving the fleet in a given direction. And that's all it does.
Another idea: "quickgrav" terrain - alluding to quicksand. It waits nearly invisible until a fleet stumbles upon it, then it strongly pulls the fleet towards its center for a second or two before the fleet's engines dissipate it.
Kind of going aside, I'd like to suggest "fuel clouds", which are like debris fields but full of fuel. Probably not a good place to fight a battle, heh.
A bigger idea: "ejection disk"s. The opposite of black holes, ejection disks push everything away from them, perhaps in a spiraling pattern. Maybe if you fall into a black hole, you emerge in hyperspace from an ejection disk?
I'm running out of ideas, by I do have one left: waves. Alex messed with the idea of riding hyperspace waves for travel, but it didn't work out. I suggest using them for getting wayward players back on the map in a hurry. So abyssal waves coming out of the abyss and (in-system) hyperspace waves coming out of interstellar space. Let them just lightly shove moving fleets, but still or "s"low fleets get picked up and pushed along quickly.
Whew, that was a lot. TL:DR - vary hyperspace terrain based on real space terrain and add small, transient terrains and stuff that break the monotony of traveling in a straight line.