I'm new to this but I'm taking the same approach as you are and trying to rotate cards I have for expenses that don't qualify for any of the >1% bonuses so it looks like I'm using all of them.

Honestly, from what I've read on here and other places, I don't think it really matters after a while because if you've opened and closed enough cards, it'll be obvious what you're doing regardless of the spending on each. It makes me feel better about it for now anyway.