My house is 1,400 square feet. I've been working on making it 2,600 square feet. We have three bathrooms, and that seems to be about right for the two of us. Odd how nice an extra bathroom is!!!
In my opinion, there is never enough storage in a house.
Open Concept is great, but it's usually poorly framed. I can't even count how many homes that I've been in with cracks in the sheetrock or crown molding that is caused by undersized lumber in the roof.
I think being able to see the TV from the kitchen is very important. My wife and I enjoy watching TV together, even when she is in the kitchen.
You can't have too much counter space in the kitchen.
Attached garage for carrying stuff into the house and not having to deal with what's happening outdoors. I think 10 foot wide doors are just right. 9 foot is tight, even with a small car. 16 foot is just about useless for two cars, and a lot of open space for one car. My garage is 42 feet wide with three separate 10 foot doors. This gives us a lot of room for the doors to open on each side of our vehicles, and also have shelves on the walls for storage. I think I got that perfect, it's really worked out well for us, even though it's not done yet, and I have stuff spread out all over the place to work on the rest of the house, it's still really nice!!!!
I like a small master bedroom. I think it's silly to have a bunch of space in a room that is just used for sleeping in. But you can never have too big of a closet.
I put my washer and dryer in my master bedroom closet. Eventually I'm going to have a second master closet. Not so much a his and hers, but just more room to store stuff.
The master bathroom should have a room with a door for the toilet. No need to share everything you do with each other!!!! We actually use two different bathrooms. My wife has the master, I use the hall bathroom. It's right outside the master, so it's just as easy to use either one, but super nice not having her "stuff" in my way.
I have carpet, wood and tile floors. Eventually I will only have tile floors. The tile is "grippy" which is great for our dogs to not slip, but also good for us to not slip. Nothing cleans easier then tile floors!!!
HVAC has to be in an easy to access area. Same with the Water Heater. I wouldn't even consider a house that has these things in the attic.
I made the mistake of going all electric. When I lost power during an ice storm, it got VERY COLD in my house. I installed a wood stove and feel that everybody should have a second source of heat.
Same thing with a generator. I'm still using a portable gas generator, but that will change eventually to a whole house generator.
Kids bedrooms should be 12x10 or a little bigger. A lot of homes will make them 10x10, which is minimum Code for a lot of areas, but that's just too small.
A office is something that's become more and more important to us since my wife now works almost totally from home since Covid. I guess a really good internet connection should be considered when moving. Ours is barely good enough to Zoom, but we have to turn off other devices that are using the internet for it to work properly.
Door width can be an issue. Especially for a bathroom. Seems like it was very popular to make bathroom doors 24 inches for a period of time. I have clients that have gotten older and require Walkers to get around, and they cannot get into their bathroom with the Walker. I think ADA is 32 inches. In my opinion, every door should be 36 inches.
When we finish our addition, the front door is going to be 42 inches wide. 36 inches is normal for front doors, but always a pain to get things through. French Doors are better for this, but they suck for sealing, and over time, they always loosen up. I personally hate French Doors and would never own them.
Water spigots all around the house. Seems like most houses are lucky to have one in back and one in front. They are also very hard to find. Same with outdoor outlets. At least one on every outside wall!! We've also become big fans of outdoor lights. Some are on switches that we usually leave on all night. Others are Dusk to Dawn that allow us to look outside a window when the dogs start barking. We've started putting installing security cameras, and the long term goal is to have a full blown set of cameras all around the house that we can record everything on to see what happens when we are not here.
Be sure to have a main water line valve somewhere before the house. Just about every house I work on relies on the valve on the meter to turn off the water. Depending on how far back the house is from the road, that can be a VERY LONG run when you need to turn off the water in a hurry. I have a valve in the ground just outside my house, but when doing my addition, I put another valve in the wall, behind a door. You never see it, but it sure is nice to turn off the water without having to go outside and reach into the ground. A lot of homes with PEX have something like this.
If possible, have the electrical panel on an open wall in the garage. Too many older homes have it in the master closet, which can be a pain to get to. Even worse is having it outside!!!
Just about every leak in a roof is caused by a vent or something going through the roof. The fewer the better. Next area of concern are the valleys. Leaves build up in them and create dams that force water under the shingles and eventually causes a leak. Dormers are also a huge issue. They accomplish nothing, but always require maintenance. The most common issue is where the siding touches the shingles. I have made a lot of money fixing dormers!!!!
For us, the back porch is our favorite place to hang out. It's 16 feet deep and 24 feet wide. I made the porch a lot smaller when I built the house and it was worthless. I couldn't imagine having a smaller porch, and bigger would be better, but this works for the two of us.
I've spent years looking at my floor plan. I can go months without seeing an issue, then something pops up that I have to change. Recently, it was the swing of a door for the pantry. I just keep looking at it and making notes so I wont forget what I need to do when I get to that point. I think it's really amazing how slow my brain is, and how much I change things over the years.