Greg, our motorcycle culture is the same but also different - meaning that depending what riding preference you have or brand your own you may find similar minded folks and events. We do have Harley, BMW, Indian events in Germany but also many sizeable multi brand rallies and bike meeting places and gatherings. For my part, I am also a Harley-Davidson and a Boss Hoss rider. As I am quite injected in the Boss Hoss community I do typically participate in BH events.
Well there are no places like Daytona beach bike week or Sturgis bike week. The largest festival of comparable nature seems to me the bike week at Lake Faak/Austria (
http://www.bikeweek.at/en/european-bike-week.html).
We do have a strong motorcycle history here in Germany and certainly in Europe with its many different brands. But not many brands survived through the years and the community seems to have grown older.
I have ridden outside Germany in Denmark, Norway, Finland, Sweden, Austria, Italy, Spain, France and Portugal. The terrain and roads throughout europe differ as much as they do in the USA. To me, it's really the people and the places which make the difference and I found that american riders are the most welcoming and sweet people I met.
On the topic of Excelsior-Henderson I have to report back on my experiences as the bike hasn't run much on german roads (yet) and riding conditions aren't ideal this time of the year.