OK, since nobody's biting, I'll go first. The Germans here can tell me what they think.
Bavaria could have been kept under the original borders, Palatinate and all. Alternately, Franconia and Swabia could have been detached as well, the former becoming its own state, the latter either becoming a state as well or being joined with some of the territory to its west.
The Baden-Wurttemberg area could have been divided into 2 states (one for each occupation zone) or seen the original states restored (with Hohenzollern added to Wurttemberg).
The Rhine Province and Bavarian Palatinate could have become their own states. Alternately, the Rhine Province could have been divided into 2 states according to the occupation zones. Montabaur could have joined either Hesse or the south Rhenish state. Rhenish Hesse could have joined either Hesse or the Palatinate.
Westphalia could have become its own state, but its borders need not follow those of the Prussian province. It could have included the Hanoverian government district of Osnabruck and the Oldenburg Munsterland. Alternately, the Westphalian districts of Tecklenburg, Halle, Bielefeld, Herford, Minden, and Lubbecke could have joined Lower Saxony.
If the northern Rhine Province and Westphalia are not joined into a state as in OTL, the issue arises of what to do with the Ruhr, formerly divided between the former Prussian provinces. It could be made into its own state, either just the Ruhr proper (Duisburg, Essen, Bochum, Dortmund, and nearby localities) or a "Greater Ruhr" that would include Dusseldorf, Wuppertal and a strip to the Dutch border on both sides of the Rhine.
Oldenburg, Brunswick, Lippe, and Schaumburg-Lippe could have retained their statehood in spite of their size. The former 2 doing so would impede the creation of Lower Saxony, so Hanover would have to be restored. Lippe could have joined Lower Saxony instead of (North Rhine-)Westphalia. The government district of Osnabruck and Oldenburg could have formed the state of Weser-Ems, possibly joined by Bremen and the district of Tecklenburg.
In the case of a united Germany, all or part of Lusatia could have gained statehood. Berlin could have either become a state or been returned to Brandenburg. In the event of a favorable revision of the eastern border, the states of Hither Pomerania and Lower Silesia could be created, though the latter would not include most of the region is would be named after.
Lubeck could have been restored as a free city and Frankfurt could have become one as well if it was chosen as the West German capital. Alternately, Hamburg and Bremen could have been absorbed into the neighboring states. Cuxhaven could have been returned to Hamburg and Bremerhaven could have stayed in Hanover/Lower Saxony.