May I ask just what is a "servery" and what does one do in a "conservatory"? You must not be in the US. It looks to me that the current family room has easier access to the kitchen than does the current dining room. That would be a plus for doing what you want to do. As of the floor plan, it looks entirely doable and it makes sense to reverse the use of the two rooms. It looks to be awkward to carry food service all the way around and down the hall to the current dining area. If you have servants, that might make sense. Since most of don't have any such, it makes sense to have the dining area adjacent to the kitchen. Most people don't even use the more formal dining areas of their homes, except at holidays. The modern sensibility is that most little used areas of that nature just amount to wasted space. So, if you spend more time gathered with friends than gathered around a more formal dining area, make that change.

You want it to be cozy and inviting but what do you want/need the space to do? Start there before you buy anything. Do you need office space? Do you have or need a place to hang guest coats? Would you use it as sitting/entertaining space or is your lifestyle such that it would only collect dust while you use the space more connected with the kitchen? I could see it as a lovely reading retreat for adults or kids or adults reading to kids with bookshelves and comfortable chairs - but that fits my life.

:) Valid questions The office room will be used as a bed room. So, I dont have a "real" office room. I do work from home a lot and that dining room would be really multitasking. kitchenette is wife's demand. So, no questions asked there :) In fact, she does lot of cooking and often cooks with spices that make the home smell like a curry. kitchenette is to avoid that. With a nice vent system, that kitchenette would help us contain the smell. We are not really thinking about the house for sale down the road in the near future. We wan to build one as we want it and live next 30-40 years happily ever after.

PAX can definitely be imposing and overwhelming—if you went this direction, you may want to consider the 14” depth instead of the 23” depth. That might be a more practical depth for toys and games anyway. Ease of operation of the doors might depend on whether the doors are sliding vs hinged, material and style, etc. I’m sure some are heavy and difficult, although mine (hinged) are not. I actually wish mine were harder for my 11 month old to open, but sadly he has this obsession with opening and shutting doors and won’t leave my Pax alone. Someday he’s going to pinch his fingers. At my last house (which also had Pax) we didn’t have much space for doors so we mounted thin curtain rods along the top of the units and hung simple linen curtains on rings. It worked and looked better than I had expected and would be easy for kids to operate.