Yeah, don't bother going to the breweries (three at least in the centre) if you don't want to try the Alt. Same with kolch (which is more like a lager) in Cologne. For folk that haven't seen it, the waiters may continually replace your wee empty kolch glass with a fresh one and update the total on your beer mat until you put a beer mat on your glass to stop.
(In other places I was using beer mats to keep wasps out the lager. They are suicidal for it.)
There are lots of liqueures/digestifs. The local one in Dusseldorf was Killepitsch (a bit like Jagermeister) and I remember an off sales across from one of the breweries used to serve it (and other drinks) out a hatch in the wall.