In all my hours of CK2, I finally started to play the Anglo Saxon in 867 instead of playing the 1066 French/German or 769 Byzies (hell even the Rum Seljuks are comfy too).
I think so far, its not my best playthrough but my most comfy. Just focusing on the British Isles, getting the Norse off my lands and keeping the Scotts and Irish at bay with strategic alliance, plot and claimant married into my dynasty.
My firstborn heir has a claim on Scotland and due to how Tanistary work, I think I will marry his kids to Irish claimants so his grandsons/daughters can claim the isles in one swoop.
In the meantime, I build, modernize England and help the Karlings and Asturias against the looming threats of the Khazar Jewish hordes and the Umayyad Sultanate in Iberia.

I see its way more fun to just keep your De Jure Empire, and let your vassal conquer and just install relatives on other thrones than just blobing and conquer everyting.
I might go ahead and conquer Scandinavia since its Christian now but heavily fractured between heatens and catholics Norse chimping out, just to have a "North Sea Empire" thing, but thats as far as it goes I think.