....treat us like you'd expect us to treat you. Smile, be polite, please and thank you's thank you.
Yep, do all the above and you might...MIGHT... be treated with a vacant smile and have eye contact briefly made when you are showered (literally) with all that the expense of that (upgraded) seat entitles you to.
Anything less and you'll think you had unknowingly contracted a contagious disease.