Personally if I were in your shoes I wouldn't want to spend a complete day on a train journey - I would either fly or go for an overnight train. Of the options KQ321 has come up with (and I can't think of anything else). I would go with either 1 or 3 though i'd allow myself longer in Vienna or Zurich. I haven't been to Zurich but I reckon you could have an enjoyable morning in Vienna - ride the trams round the Ringstrasse and take a stroll round the Hofburg and Stephansplatz. It's worth noting that Austria is in the Eurozone while Switzerland isn't (it isn't in the EU) so you wouldn't need an extra currency.

I certainly don't fancy the 11 minute connection in Nuremberg, it's a big railway station and I think your chances of missing the bus would be high even if your train were on time (I assume the bus goes from the bus station in the station forecourt which is also big and IIRC not navigable at high speed). I also don't fancy the 0630 arrival in Munich, you'd really need to be up by 6 and you may find you have trouble getting to sleep on the train. Germany is in the Eurozone so again you wouldn't have currency problems.