Hey Bulldog,
Atlas 3 rail is great for a few reasons and I highly recommend it. Of course, it looks great. But one outstanding feature: it is a solid rail, not extruded like all or most of the others. My experience has been that it makes for very smooth operation. The flex track can be difficult if you are bending anything smaller than 50" radius. I suggest you get a couple pieces and work with them cutting and fitting the rails and ties, filing the edges, etc. Just get to know the material before you start laying track.
So, let me understand this. Your train room is about 14'-6 x 10'-6". Why are you limiting your layout to 6x10 other than the reach part of it? Just a suggestion but, try looking through layout design books and other places and maybe utilize more of the space you have. SCARM software is great for creating track plans. I sketched one together for you in 14'-6" x 10'-6". See the attachments.
Planning is everything on the front end. Draw it, stare at it, draw it again. Anyway, just my 2 cents.
Enjoy.
