I need to add a computer before this 10 year-old iMac dies. I expect to be moving soon, and would like to be able to carry my computer back and forth from work, so dropping an 11" Macbook Air into a docking station with large monitors, wireless keyboard and mouse at both home and work makes good sense. The 11" I can drop into the center console of a car if I pop into a pub on the way home, so I think that form factor is better than larger, but I do love a big screen and don't want to sacrifice this.
Used Macbooks span a wide range of price, often based upon the SSD included. What I'm considering is buying something with a tiny SSD and replacing it with one that is encrypted, since my work is mostly confidential and that added layer of security would be welcome. Given this, I am not certain whether I'd actually leave the thing in the center console, but hey. . .I'll leave that decision for later.