Wall off the great room area and make the guest room with French doors accessible to the porch

Helpful...!!

Could the sun room be used as a guest room as it is close to a WC?

Right now more questions than suggestions! Do you really need a LR, Great Room, & Family Room if it's to be used only occasionally? Won't your guests be wanting to spend their time with you in "the big house"? Rethinking how it is to be used - sleeping comfortably, relaxing, some privacy .... Having a bedroom with a bath attached would be my first priority, then a large living space, kitchen and porches. Another full WC somewhere near the public areas of the place makes it easy for additional guests, and having hide a beds, or comfortable sleeping couches makes the space multi-purpose.

I can understand wanting a big open space for when you have many guests over. My family's own gatherings rarely last more than one day, so we don't need extra bedrooms, but a big space to mingle is a must!
That being said, I've noticed that totally open spaces, like what you have in your plan, get really noisy. You may want to separate the family room and/or great room from the dining and living rooms with walls and french doors, and add plenty of soft surfaces (curtains, furniture) to help with that. This also allows some versatility if you do ever need a guest bedroom in the future.

I can't read the label for the space in the lower right corner. What is that room?

You need an architect. Their cost is easily absorbed into the total cost as mistakes and re-dos will cost you more. Also, local codes may be an issue. Set backs, prevailing site lines, easements, any septic tank s, all these and more need to be addressed. I worked as an interior designer for 25 years and have come across all of these situations. Good luck.

Mohammad. I reviewed your program. It appears you are not wanting a home. You seem to be wanting a separate building for recreation and a bedroom for out of town guests. Some of the issues I stated in my previous comment will still pertain to this space. What you do not indicate is your existing home. A building like this still wants to be associated with the primary residence. The connection with the primary residence can be vital. Without knowing what your existing property looks like it is unlikely you will be happy with the results of all the comments you are receiving. You do need to consult a professional to get you started in the right direction.

My current house has lots of angles in the floor plan. When I remodel I plan to take most to the angles out. I like the views the angles bring, but they can make function difficult. Still, if you love the angles keep them.

dgmelton. If you are going to take out current angled walls make sure none of them are supporting a room or the roof above. I sure hope you take some time to do as-built drawings and review the load path of the current structure. Angled walls can work well. Sometimes those same walls eat up floor area and create some real useless spaces.

Before you invest lots of emotion and money in this project, hire the best architct in your area. Using stock house plans won't do your project justice. You want a beautiful, welcoming home for your family and friends. I am afraid the images shown don't come near achieving that.

How could you consider spending that kind of money on a house but cheap out on the preparation. It's pure non-sense... people who build 4000 sqf guest house (88' wide x 46' deep) rarely come here for advise.....

I'm sorry, but asking for free advise from people who do not do this professionally for a house of this size, is foolish. Find an architect that you admire what they've done and work out a deal to improve your house. This bandage approach will eventually fail. You will have to live there with all the rights and wrongs.

Mohammad. I understand your program. You may be lost in the details at the moment. Please do follow and trust the advice given here by all these people. You are about to embark on a reasonably expensive journey. Get professional help with someone who you can sit down at a table and brainstorm with them your ideas and intentions. There are Architects and there are professional building designers who are members of the American Institute of Building Design (AIBD) who are well versed in projects such as yours. I personally love a design challenge. After 38 years designing homes and special use buildings I enjoy this type of challenge the most. I am in Ohio and may not be close to where you are but I am sure with a little investigation you will find the best design professional for you.

mrsstem, that's what I thought as well.