In all honesty, you are looking at a pretty expensive renovation so it is probably worthwhile getting some plans professionally done. The best alterations will be site specific, so will take into consideration the local climate, the path of the sun, where the best views are, anything blocking the sun anywhere, passive solar design, privacy from neighbours etc. It's just not possible to make a great design without all that information and it would be a real shame to spend tens or hundreds of thousands of dollars and not get the best result possible. Given that you haven't stated where you live, we don't even know whether North or South is the sunny side of the house, so it's impossible to suggest improvements! I'd strongly suggest taking your time figuring out exactly what you want to achieve and how much you are willing to spend to do so. Even with easy access under the house, shifting plumbing will not be cheap (from memory our plumber had the highest hourly rate of all our tradespeople when we renovated), so you want to be very certain that you're doing the right thing and will love the results. If you can possibly keep the same roofline, that will help reduce costs significantly. I'd also suggest using this as an opportunity to improve your house's performance, by insulating, improving the passive solar design, installing a heat recovery ventilation system, buying energy star appliances and LED lights etc. It's all the things that you won't see in the finished house that can have a major impact on how pleasant the house is to live in and how expensive it is to run, and they're easier to do when you're doing a major renovation anyway. Good luck!

I was also going to suggest that you drive around your area looking at any new builds, who's building them and what Architect/Design firm has been involved. You could introduce yourself to any builders that you felt you might be interested in working with, call the Architect etc to discuss. If you can find locals to do the Job that's a plus, if there are any problems they are on the spot to sort. One of our Houzzers had a very bad experience where the Structural Engineer changed something without consulting anyone which ended up causing a major problem and expensive to boot. As annb has rightly pointed out you don't need to employ the Architect for the complete job as this will be more expensive, if your builder is good at his job he will manage everything with your input. Architects plans can be more detailed/complicated and sometimes there may be the need for the builder to check back with him/her. Big plus is that you are building where you live and are able to keep tabs on how things are going, very exciting time for you and your family

my suggestion are based on the fact that mum and dad are usually at the house alone and aims for simple two person accommodation that can be rearranged to suit a crowd...the kitchen cabinets are the only fixed objects in the room and include a tall pantry, base cabinets and/or drawers with open shelves and wall cabinets and space for several people to work side by side with a small extendable dining table, two chairs and a bench seat (also used as a place for newspaper and lamp etc behind the recliners)...a patio with big table for outdoor eating under the shade of the tree with extra bench seats that can also be used inside... there's space for a small divan or night and day lounge with a wall hung tv and the corner bedroom door allows for much better circulation space in both the living and bedrooms with preferably a sliding glass door for indoor outdoor connection with or without the original front door and, based on the size of king single beds, there's no other arrangement that would allow both beds to have a view to the lake and there's just enough space for a biw, small desk and two chairs

Thank you all for your comments, suggestions, drawings and photos, I really appreciate the effort you all put in to help others on this great platform. I have come up with another idea (see photos below) that involves putting the fridge on the back wall of the kitchen behind cabinetry doors (yes, I know I was adamantly against this!) and bringing the door of the pantry forward to be in line with the front of the fridge. The pantry door would also be cabinetry and the section of wall. I don’t really know how to explain this, but the wall the kitchen backs on to would be bulk headed out so it continues in line with the pantry/fridge front all the way to the ceiling. This creates a sort of symmetry in the doors of the fridge and pantry being either side of the cooktop, but without the worry of having to line the rangehood up with the apex of the cathedral ceiling....I think. What do you think? P.S. Please excuse my shoddy hand drawn sketches.