[Kythe42]

That's unfortunate, and it's probably why I was originally advised to have separate copies of Calibre Portable if I wanted to open directly to the library of my choice. I'm really not sure how many of the settings I've changed are library specific or general settings.

That's fine if you don't find it annoying and great if it works for you, but it's annoying enough for me not to be able to directly open the library of my choice that I wanted to look for alternative options, and was the entire point of this post. In pretty much every other relevant program I use, I open the file directly rather than opening the program and then choosing the file. I don't like the extra time it takes to load one library and then wait for the library I want to load. Everyone has their own pet peeves and what they're willing to put up with. I tried doing it that way before with just two libraries and I quickly got fed up with it.

Edit: It seems another justification for separate copies of Calibre Portable is that there are certain settings that I might want to be different for different libraries, but changing the setting on one library affects all of them.