I have a double feature request that will go very well with the upcoming VR features, as well as general use in helping to visualise the scale/density of stars, and will find a nice home next to "apparent magnitude limit" -
A "visible distance" limit, effecitvely allowing you to create a sphere of visible stars at any distance. To go with this, a "star brightness equaliser" would be fantastic too, so you could see T class brown dwarfs as easily as brighter stars, so you can get a true feel of the density of stars around you.
If you have in the data somewhere a "local star density" variable (e.g. stars per 10 cubic light years), having it visible in the stats menu would be FANTASTIC too.