Well, I've begun my trip home.
I managed to achieve my goals this morning, visiting the grave of Leopold Zunz and then making some last-minute purchases at KaDeWe.
No problems at Berlin Hauptbahnhoff getting my ticket, but I had someone help me through all the multiple screens of the automated system. This has to be one of the most complicated ticket-purchasing systems on the planet. After you finally figure out the first machine, you have to take the print out to the second where you actually pay for and receive the ticket.
My hotel in Frankfurt is only one u-bahn station from the hauptbahnhoff. I'm at the airport right now trying to pre-check in for my flight. That way, I'll only have to be at the airport by 6:00 am to go through the two security checks, as opposed to 5:30.
Unfortunately, they won't let me do early check in until after 7pm, so it looks like I'm going to have dinner here while I wait. As long as it isn't McDonald's; so far I've avoided all American chain restaurants during my entire trip to Europe.