Your dilemma is very common. Too many color choices = Color confusion
Couple of things. Going the posterboard route is the smartest thing you can do for trying to narrow down a color. Tru-Hue http://www.truhue.com/products (broken link) foresaw this a few years ago and offers paint color test boards in different sizes, even the cool accent wall ones. Check them out. We have used them extensively.
Restoration Hardware's Silver Sage is an awesome color. We have seen it used many times in the room makeovers at RoomVues.com
RoomVues - Capture Your Color!. They still might be posted in the Showroom gallery.
You might want to consider uploading or emailing them photos of your home and let them offer you some color suggestions. They will even virtually paint the walls to give you an idea of how each color suggestion could look.
The bottom line though is that the final color decision is up to you. And what might look good on a small color chip or computer screen could only act as guides. Just arm yourself with as much information as possible so that you can make a confident color decision.
I am sure your home will turn out beautifully!