room shape

I will be construction a house in the country side with pretty much a clean slate for the listening room design. This will be for a 2 channel system, not a surround home theater. I've read through the different discussions regarding room design and saw Premium Home Theater : Design & Construction by Earl Geddes mentioned several times as a good resource. Unfortunately It is no longer available at Amazon.
The home will be fan shaped so using splayed walls will actually be easier than carving out a rectangular room. I'm leaning toward an irregular pentagon (birdhouse) shape. The ceiling will be sloped. Flooring on top of concrete and most probably adobe walls. I will have to compromise with some windows due to the spectacular view at the site. I envision looking at that while enjoying music. I know that's much less than ideal, but I'll have thick curtains for serious listening.
From what I've read, building non-rectangular rooms can be more challenging. Any input is appreciated. 

Actually, you can follow some basic concepts from speaker cabinet design books!   The idea is to keep non integer relationships between the six walls.   This way no given standing wave is re-enforced.  Note that solid walls reflect bass while the bass will pass through less solid walls, such as sheet rock and OSB.   If the bass can pass through you are less likely to set up a standing wave in the room.   Likewise, dead rooms tend to kill non coherent musical distortions sooner than music, which is more coherent.  

If you are really serious about this, talk to a professional sound engineer or architect who specialty is designing sound rooms.   They will know what materials to specify and how to design the room to make the most bang for your buck.     
Spatialking, Good point WRT to solid vs. less solid walls. Obviously adobe bricks are not common in the US and there isn't too much I could find on their acoustic qualities, but they do absorb sound. Also since walls constructed this way are uneven, I'm sure they would diffuse the sound to a certain extent. Sheet rock with offset 4x4 studs is a possibility I'll keep in mind.
I've spent many hours listening near field in studio control rooms, but this is my first opportunity for a large room. My experiences with 5 sided rooms in that environment have been positive, but they have been small. Finding a specialist in the 3rd world could be problematic, but I plan to investigate that avenue.
BTW, one thing I forgot to mention is in a larger room you need speakers that can comfortably fill it with sound.  That is, they need to play more loudly with the same clarity and definition that smaller speakers would play in a smaller room.  

I am going to guess that most of us probably have speakers that should be in larger rooms than we have.  I am certainly guilty of that.   If that is correct, then perhaps this is not as much as an issue.
Though I haven't had any connection with Michael Green, I think he would be someone to contact, given his CV.