We built one for a friend years ago. 18X30 with a covered concrete front porch running the full length. It originally had an outhouse but has since been upgraded to a real bathroom with shower. If you opened up the floor plan, you could sleep 6. Very comfortable. Electric baseboard heat, electric on demand point of use hot water. Small kitchen area on one end wall, dining/living area in the middle, sleeping/bath at other end.

Northerner and Vesty, Those are pretty sweet cabins!  

Get a 12 x 14 to a 16 x 20 wall tent and stay in it a few weekends to try the size,build your cabin to fit your needs,then sell the tent.
The bigger beams on small cabins adds character in my opinion.
I bet you will build a few feet bigger than you thought you needed.

We have a 12' x 18' cabin with a 6' porch and we spend many family (2 adults, 2 kids and a dog) and hunting weekends there each year.  It's the best thing we ever did, I don't think you'll regret it if you do it.
-Jay

Wow! Those are some nice looking cabins. I would definitely want a porch on it.

23feetupandhappy that is a darn good lookin hunting cabin..