Hi guys, sorry for the confusing title, but what I'm looking for is a few recommendations on bags that function primarily as laptop bags, but can also be carried in a somewhat hidden "backpack mode"

To make it clearer, here are two examples that I've researched:
1) Tom Bihn Western Flyer (current leader)
2) Tumi Alpha 3 Way Brief

Also, one more thing I forgot to add is that the bag cannot be overly big. In a pinch, I'd like it to also have the option to potentially use it as a "personal/underseat item" in addition to a standard rollaboard if necessary.

I know that personal item rules are vague and a lot of it has to do with over/underpacking, but for example the Tom Bihn Tri-star is already too big of a starting point for me, so I'm looking at Western Flyer size or below. I like redoxx stuff too but have not found one of their bags that fits what i'm looking for.

thanks for any recommendations