Since your Blu-ray player's zoom is causing noticeable degradation of the picture,you might want to consider going with a Blu-ray player which utilizes the Marvell QDEO video processing chip (and has multiple precise zoom and aspect control options) .
A couple of options for such Blu-ray players are the Cambridge Audio units and the Oppo decks .
Any degradation should be very minimal and difficult to notice if you go this route unless you sit very close to your screen.
The only way to avoid both the black bars and any degradation at all with movies formatted wider than 16:9 .... at the same time is to use a 21:9 screen .
I made 2 more detailed posts under the similar question here : * http://www.soundandvision.com/content/how-do-i-adjust-movie-images-fit-m... * .
I think that offering multiple aspect ratios of a given movie on the same disc might be the best solution. Maybe they can do it that way in a couple of years as the data capacity of Blu-ray Discs expands .