The old city center, the Altstadt was properly bombed in WWII, but there are plenty of rebuilt buildings. (Too see what Frankfurt looked like right after WWII, take a trip to the South Bronx or Detroit before leaving for Europe). Don't dwell there, and instead head to the Alt-Sachsenhausen district, full of cobblestoned streets and taverns serving the famed Ebbelwei (aka Ebbelwoi or Äpfelwein, i.e. apple wine), the local drink of choice. It comes in different grades, and avoid the Rauscher if you would like to get the cheaper standing room ticket at the stadium.
Which brings us to the reason for our visit, namely the rich soccer tradition. It starts with Eintracht Frankfurt . The Bornheim district is the homebase of FSV Frankfurt , which will always be bouncing around the upper echelons of the amateur leagues. It is definitely worth a visit to check out a game. Among other teams to look for are Rot-Weiss and Progres. The latter had a memorable season in the 1995/96 Hessen Oberliga, as they only managed 5 pts, 16 goals scored and gave up a whopping 142.
Heading south on Autobahn-5 for about 30km, we come to the city of DARMSTADT. Nothing to see here, although the area around the Herrengarten park has lots of pubs and restaurants. The local soccer club, SV Darmstadt 98 was once in the Bundesliga, but has degenerated into a bottom feeder Regionalliga club that probably needs bankruptcy or at least relegation to set things straight. The next stop is the small town of BÜRSTADT. Continue south towrds Mannheim. It's basically across the river from Worms. This is the home of VfR "Oli" Bürstadt. They've dropped Oli, but they're still a scrappy little Hessenliga caliber team that once played in the Regionalliga. That's pretty much it for south Hessen.
Heading west from Frankfurt, we come to the Taunus region, which is often described as "an unspoiled landscape full of hiking trails, etc.", which almost would put this whole area in the "who cares" category. In fact, you can actually go to the city of WIESBADEN, which is particularily disgraceful. They may have a soccer club, but they're total crap and nowhere to be found. (For the record, I think it's SV Wiesbaden.) I suupose there are some reasons why you might want to visit, but if you've already been to Vegas, take a "been there, done that" attitude. But luckily, there is some salvation. Head north on the B54A for about 5km in the direction on Taunusstein. There, about 1km away west on the B275, is the village of WEHEN, which is the site of a scrappy little club named SV Wehen.
Immediately east of Frankfurt, practically a suburb, is the city of OFFENBACH, which has a rather illustrious soccer history, albeit tainted at times. The local club is famed Kickers Offenbach, which is also known by it's nickname "K.O.", which is their usual state being. In good times, the fans like to refer to "OFC" instead. Tour guides always ignore Offenbach, so rest assured that there will be little in way of distraction to prevent you from checking out the soccer scene.
Heading northeast, after about an hours drive (30 minutes if driving with most Germans), you arrive at the town of FULDA. This area was made famous during the Cold War as the location of the Fulda Gap. If you're like most Americans, you figure this was simply the local store where you could buy jeans, but in fact it referred to the location where the Reds would come pouring across the border and destroy our way of life. Of course, once Kentucky Fried Chicken showed up Beijing, and McDonald's raised the flag over the Kremlin, the Commie states collapsed like a deck of cards. But even today, "Fulda Gap" still has a meaning: it refers to the defense of the local club Borussia Fulda , which gave up 3 goals to "KO" and lost the playoff spot in 97-98. Aside from soccer, Fulda has lots of museums, and in fact the local tourist office sells a Museum Passport, which gets you into all of them. Use this to your advantage by informing your wife that you also need a visa, and that you have to head back to Frankfurt to get one. This should see you safely out of town after catching Borussia...
Just about the only soccer is northern Hessen is played in KASSEL, which some tourguides describe as having "the dullest city centre in all Germany." Unfortunately, you may come at the wrong time, as the local club KSV Hessen Kassel has a policy of going bankrupt every 5 years or so, so who knows what the future will bring. They were changing their name every other year to escape the tax-man, but they will eventually run out of variations of "Hessen" and "SportVerein". If you're feeling sad, drive out west a bit to the Edersee, where you could thrown yourself off the dam. Or you could continue on the village of Korbach, where yours truly had a memorable experience of being on a school trip, marching through the country side singing incomprehensible songs (my only vocabulary at the time was "Verdammt nochmal!"). I remember that we stayed at some Herberge that was built for the Hitler youth. But it was a valuable lesson, in learning that one of the essences of German character is to march through the forest singing incomprehensible songs, and this insight allows me to write Abseits today...much to your chagrin, no doubt.