I think I have made my decision, Hamburg will be the NOVOTEL DORINT HAMBURG ALSTER. Berlin probably Choice hotel the Comfort Inn Fruehling am Zoo.
I am emailing the hotels for directions from the train station.
Thanks again

Just want to stress once more that there is not much to look at or walk to in the area around the Dorint Novotel Alster (even no restaurants in the near vicinity).
Savings compared to more centrally located properties (and I noted that upon a check with hrs.de the Renaissance was cheaper than the Novotel) like the Renaissance or the Intercity Hotel Hauptbahnhof should be substantial.