How deep is that recessed wall in Plan B with the screen? It looks deep enough to do an AT screen with your LCRs and sub behind it. Which would be awesome.
However, I personally prefer plan A for a few reasons:
1. Surrounds on stands next to your seats is lame. This is only acceptable if your in college or have NO other option IMO. Plan B keeps the surrounds on the walls. Even better would be in wall speakers giving you a much cleaner look. If you don't have surround speakers take a look at Triads In-wall line up.
2. You could still do an AT screen (as mentioned above) by making a false wall with a few 2x4s. Very little skill required, but you need basic tools.
3. The door way issues (ambient light and sound) can be addressed with heavy curtains.
4. Totally personal preference here, but I hate having the only doorway to a room at my back. Plan A fixes that.