I have not flown that route, but have flown to Frankfurt and have transfered there. Not my favorite airport to transfer, but it is the easiest Airport if headed by train to anywhere as in Europe. There are a ton of trains that pass thru and you can get a train to just about anywhere in Germany. Koln would be an easy trip as would Heidelberg. Leica Fan? head to Wetzler. I know Frankfurt gets overlook as its a "modern" city and not a old German town for the tourists, but you can find "old tourist town" its just tucked away, you can find it if you look.
Another option and perhaps easier would be Qatar Air.
