Having both too, I do agree for movies and series, especially HDR ones.
Having said that the OP use cases did not include movie watching ("I will primarily be doing some light work (email, etc) and then watching/playing games and possibly doing minor photo/video editing (son likes GarageBand, I like to tinker in iMovie)"). Still, I find the larger size better for editing and for basically anything else as long as I am at home and can put the iPad on a stand most of the time.
Where the 11" shines is on the go and for things where you would hold the iPad for a while, like reading.