I keep stuff I want on an SD card, so I just move that from phone to phone.
Everything else, Google backs up. When I turn on a new phone and enter my credentials, it just starts coming down to the phone. I just let it re-download all my apps, and then all my custom ringtones and whatnot are there. Then it's time to set up my groups, my one-touch text and phone widgets, and my home screens.
To that end I've simply taken screen shots of everything and stuck them away. I'll be able to re-arrange everything to my liking on the new phone.
And of course, my SD card will be there with everything I need.
Oh--and I also use SMS Backup and Restore to backup texts and phone calls. I then restore those to the new phone. That won't work when RCS lights up, by the way.