Former East Germany is a great place, quite rural, somewhat less expensive than what used to be West Germany. The Germans have poured massive amounts of money into the east for redevelopment, and it shows - all the cities are nice, bright, restored and renovated.
I toured all of Germany last year, and enjoyed the former DDR most of all.
Berlin is a huge city, I found it stressful, but I don't like cities to begin with and usually avoid them when I travel.
Poland is a very nice place, I rode through the southern part, along the mountains, last summer.
Good news: Lots of ATM's (they accept Western European bank cards), credit cards are accepted at just about every gas station (many of them, you just shove your card in the pump, just like in Paris or London), nice people, cheap food and lodging.
Bad News: Roads can be in poor condition and very rutted from heavy trucks along the major highways and major urban through-routes. Secondary roads are often better, more enjoyable, and have less traffic. Theft (of the motorcycle) is a major concern. Be sure it is parked in a secure, guarded location at night. If you stay in a B&B or pension, put it in the owner's garage and have the owner then part their car (or tractor) behind it, to prevent it from being stolen. If you have a rental motorcycle, I doubt that the insurance will allow you to take the bike into Poland - check this ahead of time.