I'm jealous, both that you have the new one on the way and that you have two others that will still fetch a nice used price! I usually keep my iThingies so long before upgrading that the old one is not worth much and better just kept as a backup. For example, I upgraded from an iPad Mini 2 to my iPad Pro 9.7. I just kept the Mini because I would have basically just been giving it away at its current market value. Always nice to have options like you have!