A lot of the adventure books had more detail. For example, the House Devon, House Jade-London, and House Kashmere books had additional details on the House worlds for each of those Houses, respectively. The Durandium Find has several systems for House Carlisle (or was it Augustus-Hayes?). I remember one summer in the early 90's I actually added everything to a single star map on graph paper, though it's long-since lost.
Many years later I found a cool reference that showed every star within 100LY of Sol. Turns out there are quite a few: something like 1 every 125 LY3, though most are red dwarfs.