Post over in Home Decorating. Lots more activity there, and people who are real whizzes about this sort of thing.

Wow, er612! Thank you so much for all your ideas and your effort!! The pictures definitely help me demonstrate what I've been trying to explain to my husband (and will need to explain to a contractor). I'd love to go with the simplest option, but as @AnnKH mentions, sound is definitely an issue; we can't even make a cup of coffee in the morning without disturbing our daughter. But visibility/privacy is not an issue, so I really like the first picture. @AnnKH, we used sun tunnels in our last home and loved them, but our condo association has some restrictions. And a solid wall would mean A LOT of wall, given how high the ceiling in our living room is. But your point about sound insulation is well-taken. And it's funny that you mention a vacation home, because I've slept in my daughter's room on occasion, and it definitely reminds me of being in a rental condo like that. I can even hear the dishwasher running, just like on vacation!

Either way, it won't add any additional value to your home. I'm an appraiser. If I were to appraise your property, I would increase valuation if you added square footage, finished incomplete interior space or added a bathroom. This doesn't mean that this space won't be more attractive to a potential buyer. It might make the home more easily marketed with an additional bedroom. It may make the space more usable for your family. It just won't add to the total market valuation. So, don't do it for that reason. Do it because you want to do it.

I think you got better starting advice from the 2 nonPROS. The term gas chamber is so disgusting just ugh. Its on their wish list so obviously they want one, as as we debated before, contrary to your opinion, most home owners would like to have one. And Patricia, you offered nothing. If you cant or dont understand a pretty clear question, skip it and come back later. Edit: Also , dont post your entire floor plan (if you are set and ok with your floorplan) if you just want advice for your loft. There are a few people that will tear it apart in sn effort to save you from yourself.