One cool thing you can do is play several countries over the span of a game and when you drive a country into the ground or get bored, you can just switch. Also good for this is roleplaying the ruler as your character's traits suggest. For example when educating kids, if your character is slothful, pick the option that makes the kid slothful too, if they're zealous go for the 'Pray for their soul!' option, and so on. If your character is cruel and arbitrary, play them as such even if it pisses off your vassals. If they're kind and trusting, be that, even if it means letting a duke overreach and grow worryingly strong. If you've got a lunatic or possessed character, go wild! In one game I unified most of Scandinavia under a Norse Sweden that eventually collapsed when my vassals decided my cruel, wrothful and arbitrary king who imprisoned and executed people for the slightest infraction wasn't a nice guy and to cap it off the Holy Roman Emperor attacked; I took over half of the Iberian Peninsula as a Zikri Muslim state then got forced out of power and ended up a pretty weak duke; and I ended up turning most of the dukedoms and several counties in France into Prince-Bishoprics because of a zealous, possessed queen. It's a fun way to play, especially when you switch countries and see what the AI makes of your country, such as seeing Sweden dissolve into squabbling Norse dukedoms and counties, or seeing Zikri Islam spread across Spain and into northern Africa until Sunni Islam became very marginalized. It's also a lot less stressful I find, because there's less of a compulsion to win and optimize things and so on, and more one to let pseudo-history run its course and see what you can make happen and how far you can push things.