Free Tree House Plans
My sister and I thrived in our tree house as kids. We refused as the summer heat turned to crisp fall to not spend a night a outside despite the mosquitoes. My father only built the best and the Free Tree House Plan is pretty similar to what I remember. Ours, like this one, was more of platformed playhouse, but it makes the design applicable to any yard.
This one comes complete with a plan for a tower and porch. The closed in walls provide some privacy, and if you allow your kids to sleep out, the walls were great protection from the elements. Just click on the image for the full how to woodwork guide.
If you are considering a playset for your backyard, you might want to ramp it up to a tree house like this. You will get years of use and when the kids are older, you will have a back yard shed. I even have a neighbor who took a similar tree house plan and built his play set off of the side. The tree house was a great structure.