I do a lot of reading regarding my aircraft but also I keep looking up things in my ATPL folders, anything from meteo, performance, air law etc. to keep my general knowledge about aviation up. There are also many useful links to discover in the various threads in Pprune.
Generally, I enjoy the vast quantity of days off...it can be frustrating though when scheduled flights (we can view booked flights on the ops homepage) are cancelled on a short notice. Those are the days off, I wouldn't really need...
People are also amazed when they ask me about my last/next flight and I tell them e.g. 2 weeks ago/(maybe) in two weeks.
A nice aspect of this lifestyle is though that sleeping in is not only confined to the weekends
