Love, love, love the shower and mudroom ideas! What fun...and Mut's bike track! Your boys would be in heaven.
As soon as you get started on this project, I think detachment will be a LOT easier. You'll have something on your mind all the time other than W - and that makes all the difference in the world.
It's funny Murphy beds are becoming so popular again. I have a friend who just built a house with two of them in the media room. Smaller house, but with more options. He actually built his house in his barn - he put up this gigantic barn, half of it is shop, pool, karaoke, and the other half is house. I guess you can save on taxes that way. Very interesting approach.