Ive only been in Frankfurt to go to the damn airport and fly to north america, lol but my mom and sis sure liked going shopping there.
Never been to Munich but been to Nuremberg... nice for shopping and eating and sightseeing too. And dont forget the oktoberfest down there... but thats in a few months...
Nuerburgring is nice too... my sis has been there for a Formula 1 race a few years ago, ive been there for Rock am Ring... sure was a lot of fun!
Ummmm... id say go to berlin... berlin is always good but since you are on the other side... damn, you should take a trip to the east and see Berlin, Dresden, Leipzig. All awesome for sightseeing.
Watch some soccer games! Enjoy the craziness of german soccer fans!
Im sure it will be crowded in some places... Munich for sure, Stuttgart maybe... i know there are games in Berlin and Leipzig. Im kinda glad Im not there right now, lol
Thinking about it... go to the north too... Ostsee, Nordsee... awesome areas up there!