I suggest you do one at a time.

I don't know about YMMV, and I'm not sure why it should matter.

Most people are denied if they apply for another personal card while still having one open. Do you really care whether it's "all" people or "most" people, if you can't predict which camp you'll fall into? Just assume it's "all" people.

I don't know whether we have enough data points on business cards. I assume the same might apply for business card, because I'm risk averse.

But other datapoints suggest BofA is paying more attention perhaps to inquiry counts than before.

So I would suggest a couple things:

1. End up with a BofA card which you'll "never' cancel. You might want to therefore convert your personal Alaska card to a no-AF BofA card (it doesn't much matter which one, just use it once every year or so for something small to make sure they don't close it for "inactivity"). I don't think you can convert the business card, only the personal card probably.

2. Don't close both cards at the same time. Keep one card open while you close the other card, and then try applying for the other card. If you succeed on the other card, then sometime later repeat with the first card.

3. Remember, with a business card application you'll be either approved or denied. With a personal card application, you can be approved for Signature at 30k bonus, or approved for Platinum with the dreaded 5k bonus (more likely than being denied outright).

4. And, of course, remember to lower your credit limit right away (if you haven't already), no matter when you plan to cancel (or convert) each card.