Janice, the traditional arrangement that most of the forum here would settle on is probably with the doors opening behind the second row, screen all the way to the left. My room is 12x21 (more or less) and has that general arrangement. The challenge in this scenario is getting the doors and riser to play well together.
In my case, the door is built up to riser height, with the step up to my 14" riser outside the theater. That leaves the riser to be 8" deep and the first row of seats ends up about 9.5 feet from the screen, which is 2.5 to 3 feet off the far wall - with the speakers positioned behind a acoustically transparent screen. This puts the first row viewers' eyes about one screen width back from the screen, but note that this is a 2.35 'scope screen (extra wide). In other cases, especially with the door relocated away from the center of the wall like you have indicated, the riser can be basically the same size maybe 8 or 9 feet deep, with a small landing cut out to give the door space to open into. If you were to do this, two rows of probably 4 seats would be nice in a room 15' wide. Again, I think this would be near the forum consensus for your space
If you were to decide to go the other way, as you've indicated. The acoustics become a little weirder. The rear row gets pushed closer to the rear wall - and that becomes a "problem" for a couple reasons. Bass response is generally very uneven near the walls. Also, if you want to use the latest speaker arrangement technologies and take full advantage of the 7.1 soundtracks on some of the new Blu-rays, you'll want to allow some space between rear surround loudspeakers - normally placed on the rear wall - so that the loudness doesn't overwhelm those seated nearest. In short, the best sound is generally confined to a small area - maybe the center 50% of the room, give-or-take. Further, if you allow 7 feet for the riser, so that you can walk past each other while the chairs are reclined, the front row ends up about 8 feet from the screen. That's going to feel too close for the screen size that the room will "want." So, building the room along the short dimension makes the front row too close and the rear row sound poor. You can fit in more seats that way, so that's the trade-off. If you really need seating for ten or more, that might be the only way to do it (in 15x20 - 20x25 would be different), but there are other reasons you may not really want 10 people in the room at the same time - we can save that conversation for later.
One other thing - if you want to contain the loud sounds of movies within that media room, you do not want double doors.
Okay - one more thing (
) - there are other things that you may want to consider changing - like the routing of that HVAC chase, and probably more. How far along are you in this process?