I use the actual map of stars in our local arm of the Milky Way. We have “Warp Drive” Warships (jumps that caused new filaments and sparked a war); “Folding” Guildships (a mythos-driven low-time dilation jump); “Stringing” Ringships (grasping onto existing sub-space filaments). So I get to use a calculator each time they want to move large distances (say Saturn to Jupiter during opposition – takes 5 day or you can blast your way there in about two years.)
