This is not so much a question. It is more the summary of a newbie's uncertain frame of mind. My brain has reached this point after seemingly endless research into the whys, and why nots, of class b...
The winnebago View & itasca Navion are similar in size to the serenity but has the over cab bunk. It's also on the sprinter chassis. Why not check those out too? Heck, you can buy a low mileage gently used one for around $50k... if you don't feel like paying over $140k for a new 2015 rv. I owned a 2008 View and loved it.