I use EFIS, a full FMC and EFIS add-on for FS98. In simpler terms, I can program in the waypoints, VORs, NDBs, etc, and see the moving map on the screen. As in real life, I can have it fly the route all by itself, and even land itself! It's kind of hard to explain without using difficult terms. Check out the web page for the new EFIS 98 that will be coming out in a week or two:
EFIS 98 Web Page
It is all totally realistic; for airliners of course, not Cessnas, etc.