2017 12" Retina MacBook 16 GB + SSD - This 2 lb beast is my road warrior for business usage, and it's also great for surfing on the couch and in the bedroom.
2009 13" MacBook Pro 8 GB + SSD - Just for various around-the-house type computing needs, guest usage, and occasional road trips with the kids.
2008 13" white MacBook 4 GB + SSD - Kitchen and breakfast bar surfing and recipe computer.
Although the Retina MacBook is best for meetings and business trips or lectures, I take the 2009 MBP instead of the Retina MacBook when on short trips in the car with the kids even though the MBP is over twice as heavy, because I'm afraid my young kids might break my precious Retina MacBook. I'd cry less if they broke my MBP. I actually have High Sierra running on that 8 year old MBP though, and as mentioned, I've upgraded it to 8 GB and SSD.
The white MacBook is one I truly wouldn't mind if it got broken by the kids, but it isn't very good for this type of traveling since it's stuck on Lion. This introduces incompatibiities, such as the fact that it won't properly tether my (now iOS 11) iPhone via a wired connection for cellular, and the fact that it is stuck with old unsupported browsers. At home for recipes and basic surfing it's fine though, with its 4 GB and SSD. But even watching YouTube on it can be irritating, since it has no hardware h.264 decode acceleration.