GridBagLayout. Does pretty much all that you need (kind of) and it's in the Java library. Admittedly it does need some help, and the API is terrible.
GroupLayout makes a real mess of your layout code. Okay, so most people's GUI code is a big ball of mud. But your's does not have to be! Perhaps a nice interface could be put onto this layout manager, but I suspect it might have to be cloned-and-owned.
I am not in favour of introducing external dependencies unless they are really necessary. Also a lot of the third-party layout managers use strings of data, which have all the usual issues.
