I like to bring books that don't have a real plot, so a chapter here and there can be read without missing any plot points. Books by comedians are always fun- also, travel memoirs are good- "The Sex Lives of Cannibals" by J. Maarten Proost is really funny!!
Our favorites in the office are books by Stuart Woods..The Stone Barrington series...very easy to read..some chapters are 2 pages long...not too crazy about some of his other character weries..look for the Stone Barrington
Just a note - a couple of former coworkers who are avid readers did NOT like the Janet Evanovich books I loaned them. Probably the OP's better bet is to start with the 'between the numbers' series' - Plum Lovin', Plum Lucky, Plum Spooky, Plum something-to-do-with-Christmas... or at least read the higher numbers first. Fourteen isn't nearly as graphic as one...
Most in the Shane Scully series by Stephen J Cannell have very short chapters - great if you like the gritty detective type novels (& there is a strong female lead character too).
For cute mystery stories that are easy reads: Carol Higgins Clark. Her first in the series is "Decked" that takes place on a cruise ship, but you can probably pick up any of them and catch on to the characters right away (as she tells about them in each one). I think you'll really like them.