While I agree with Jautor about how you can never have too many displays and that you'll like a fixed screen better, I can appreciate wanting to save the wear and tear on your PJ bulb. I'm currently in that some boat, but right now I have a 100" fixed non-AT Onyx screen on my main viewing wall with a 55" plasma that is on a rolling stand that I move in front of the screen when it's just me watching casual tv...thus part of the reason for the name of my current basement renovation...The Sanford & Son Build. My project is more of an open media room/theater with bar & pool table, much like it sounds like you want yours to be.
Unfortunately, my space is much more broken up than yours is...I'd love to have your space as a blank canvas. My two cents after looking at your floor plan would be to frame over/blockout the window on the right end of the "man cave" designated area and mount your 60" and drop down screen there. At 12.6' wide you should be able to get a good 120" drop down screen in there comfortably since you plan on it being acoustically transparent and don't have to worry about leaving room for speakers. From what I know, just be sure you go with a good tensioned screen to avoid wrinkles. You'll definitely have to spend a little more for a good electric tensioned drop down screen over a fixed screen, but at least it will give you the flexibility you're looking for.
From there, moving towards the left side of the room from the screen, you have space to have two rows of theater seating using risers -or- a nice sectional unit if you're keeping it casual. You can build and in-wall A/V cabinet under the stairs where you'll have access to wiring. I would certainly consider a snack ledge type bar with stools directly behind your seating in addition to having a wet bar on the far left wall. Since that is right next to your water heater and sump, you could easily and inexpensively plumb it for a simple bar sink at minimum. Just having a sink is convenient for ice and rinsing glasses, etc.. I don't know how elaborate you plan to get with your bar build, but you have plenty of room no matter how you decide to go. There are definitely plenty of good bar threads on AVS to check out in that regard.
Back to Jautor's point, I would definitely put at minimum a 32"-37" TV in the bar area in addition to your 60"/PJ on the other end of the room. 37 feet is a long room, and by adding another screen in the bar you'll create a nice atmosphere down there. Looking down the long length of the room will be better for viewing and speaker placement throughout. It's really about the only way I can visualize it being finished, since 12'8" doesn't give you much throw distance for a PJ anyway to project on either of the long walls. By the way, how high is your ceiling down there?
If you want to check out what's going on in my similar renovation, check out my build thread. Good Luck!http://www.avsforum.com/t/1506118/the-sanford-son-basement-redux-home-theater-build