I'm in the middle of doing this planning right now. I'd started down the path of building a milled log home, but have now changed to a post & beam, with SIP walls and roof. I've "wasted" far too much time with graph paper, pencils and erasers. I've tried several "consumer grade" home design packages, and was always very frustrated with them, until recently.
Though not powerful enough (nor specialized enough) to design the actual post & beam framing, I've found the Chief Architect consumer line of Home Design products to be absolutely great for finalizing a floorplan, putting furniture in it, and doing 3-D visualization and walkthroughs. It's really easy to get started with.
Home Design Software - Chief Architect Home Designer Software
The Pro version (in addition to the Chief Architect line iof CAD programs) is powerful enough to develop final plans in, if so inclined or skilled enough. The less expensive versions will produce .DXF output that can go into professional CAD programs, which is what I'll do to have a "pro" finalize them. Even the consumer-grade Home Design Suite will produce a draft framing plan (plus bill of materials), to start preparing rough cost estimates. and allow you to create an electrical plan.
The great thing about something like these programs is that they allow you to easily play "what if" and see the results fairly easily. You can move furniture around, and see what fits. You can move doors and windows easily. You can try different kitchen layouts. You can finalize all (or at least most) of your design decisions on your own, before you start paying someone to make changes to the plan -- or even worse -- start issuing change orders to the contractor during construction.
I've tried several "consumer home design packages" over the years (IMSI, Punch, etc), and this is BY FAR the best/easiest to use that I've come across. Here's what I've generated in a matter of weeks, in the off-hours, putzing with it, starting from my own sketches. I can produce similar internal 3-D views and record walkthroughs. The best thing is that I've now been able to get the missus completely engaged in the process -- because she can now visualize the end result, which is something she simply couldn't do looking at flat paper sketches or floorplans...
This doesn't specifically answer your initial question, but it can certainly help bring the answers "to life" so you can visualize them.