This is probably the most interesting "which bike" thread I have read in this forum.
Some observations for you (strrygrrl) to consider:
You seem to be better informed about dutch style commuter bikes than 90% (or even 99%) of the regular posters here. Most of us only have first-hand-knowledge of "american style" commuters, that is why most of the replies you will get will be suggesting that you get one of those instead.

About the bikes suggested:
Reliability is premium since this will be your only form of transport. But please be selective on which info to believe in. The original dutch style bikes like Kronan (originally Swedish) and Batavus have served europeans well for the last 100 years or so. The later modifications (e.g. internally geared hubs) are the points to be sceptical about.
Rust is natural on the dutch style bikes. Of course aluminum frames will not rust, but some of the components will if the bike is stored outside for years (or decades). E.g. the chrome lights, handlebars etc. but this will not change the functionality of the bike.
You mention that a partial chainguard is enough, you probably realize that a full chainguard will be better in protecting the chain from dirt and thus reduce the need for maintenance.
I believe that Kettler is quite big in German commuter world, I would imagine that they are reliable.

Please let us know what you decide to get (and post some pictures ).