One thing I would add is that, if your preference is set to aisle, this is not taken into account when travelling on a basic (hand-baggage only) fare.

I don't do these that often, but when I do, even as a gold I find myself in a window seat probably 3/4 of the time, despite sharing your aisle preference. (Never middle at least!)

As such, depending on the route, the "plus" fares that include seat selection (a week before travel for a bronze, but that should still virtually guarantee an aisle seat) and a degree of on-the-day flexibility are probably better value, especially for business travel.