Improving upon Goober's idea from a few years ago...
Press Alt+J, get that system viewer screen, click a planet, hit jump to and watch yourself be transported to your destination!
Of course this doesn't have to be a navigational system, it could used just for reference purposes to let people explore the system they're in. Outside of gameplay the Jump To button won't appear. As well the script allows for per-mission system loading (so the map can change as your campaign's events unfold), as well as a simple hierarchy of map "zoom levels".
Like below in this test Sol layout, you can click on Earth and "zoom in" to load a new map that's just Earth and the Moon.
There's lots of other little customizations you'll be able turn on or off. Orbits can be turned off, icons can be added. You can even draw arrows to show fleet or force movements!
All I need to do is stop starting new things and actually finish what I start...