So this evening, after bottling up the really light beer, I created a settings file and a shell script to start up Devil's Pie, followed by the applications I always want running. Then I added this script to the list of programs that are run when I log in.
And presto: instant personalised settings! And quite easy to set up, too.
If you find yourself always moving windows around, or going to a particular desktop to start up a particular program, Devil's Pie is what you need. Just define a rule, and the program will automagically appear at the designated place on startup.