What a useful thread. I had a 5 hour layover and got out for a very nice run in the woods to help me get over my jetlag. I made the semi-mistake of deciding to base myself out of the Lufthansa arrival lounge (named the Welcome lounge). The problem is that they are not allowed to keep unattended luggage unlike the inside-security lounges. So when I left for my run I had to store my carryons at the left luggage facility (total charge of 13 Euros).

Otherwise the route from the terminal is pretty straightforward if you do a bit of Google maps recon beforehand; turn right out of the terminal for about 500 meters until you reach the FRAPORT hq building, take a left and then you will quickly join the bicycle path that takes you to the woods.