The Universal cottage has 2 full stories...what cost savings (or additional costs) would a 1-1/2 story version provide?  It would be much like this (on the Firstday cottage site):

And it would provide bedrooms upstairs like:

Could you go from conventional 2x4 construction to this post and beam style for the second floor somehow, or would the home have to be post and beam too?  To get the look, I think tongue and groove for the roof sheathing?  Would the cost be offset by building only a 1/2 story vs the full story?  I envision the hall, bathroom, closets, and over the stairs as loft storage or small getaway room.  I'm not sure if a low shed would be be required over the stairs for headroom (or maybe a skylight that opens to ventilate the whole house).  
The 1.5 story, gable entry is the style of just about every farmhouse around here that isn't a cape style home.  Would a change to this style make sense? Cost more or less?  I know, a lot of questions, many opinion type, but we had this vision of our house long before we came upon John's site here and when we saw his Universal Cottage it was BAM! this is what we had been dreaming about...all but the 2 stories, a lack of a pantry, and we only need one bath upstairs....everything else is perfect!  Would it be worth is modifying John's plan to fit our dream or would we be missing alot by deleting the attic space?  We will have a full basement so storage is not an issue.  Thanks for any comments (and any ropes to pull us back to reality if we have floated out too far over the edge).

This is more like the 20' wide 1.5 story.  
http://www.jshow.com/y2k/listings/50.html.

However, the Firstday system is modified post and beam framing with 2x6 car decking on the roof and walls if I remember right.

You could do a standard balloon framed stud wall and then put a beam and deck timber framed roof as shown on top of it. You might add an extra top plate to make for a stiffer span for the point loads. The roof would need more expensive foam insulation on top of the decking.

I am eyeing up the universal cottage myself. My question is can the second floor just be a hugel oft then in time go back and add bathrooms or subdivide into bedrooms?

Might want to get the upstairs plumbing roughed in.  I expect it would save some tearing out on the ground floor when the time came to work on the upstairs.

But if the plans are designed for story-and-an half loads, they should work for most anything--except maybe a practice area for the duo-pianists who really need the big grands so they can see each other when they play.  

 
I went and bought the plans last night. I just have a few adjustments I need to make.
I hope by the end of next summer we will have this home up.

Good job, StinkerBell.  Now the fun begins.

I have most of John's plans and they are well done with many options, besides being easy to modify.