Lots of these suggestions are for a long term home, they make less sense for a 5 year hold.
Split AC as previously mentioned are awesome.
Instant hot water tank, plumbed with a small day tank closer to the kitchen. This mitigates the Instant Hot Water Tanks biggest negative. In a kitchen where water is turned on/off the tank turns on/off and you get hot then cold then hot water at the tap.
I prefer a 2 step Spray insulation. Closed cell for 1/4 to 1/2 the stud cavity and then open cell for the balance. Keeps moisture from condensing against the inside of the exterior sheeting. Closed cell homes are noisier, the open cell will dampen noise down. You can also use batt insulation on top of the closed cell, but I've not been 100% happy with any of those installations.
Consider Allowing a ventilation space between your roof and the spray insulation. Spraying right against the roof sheeting can cook shingles as they are so heavily insulated from behind. Speak to the roofing installer and figure out the roof requirements.
Overhangs are king.
Keep wood siding & exterior finishes protected and accessible. The more maintenance required, keep it easier to access. The harder an area is to access, the more durable the finishes should be.
I prefer aluminum clad windows. Dont waste money on Argon fill. Go with a better coating.
Understand the orientation of the windows to the sun throughout the year. We try to build with windows that will be 100% protected from the sun throughout the summer. Even here in Canada, that's usually only a 2' to 3' overhang.
Passive ventilation, functional skylights that open can often cool a house without AC. Arrange for an air intake (open windows) somewhere on the Northside of the house or the basements.
If you are going to have lots of lights and different switches, I'd change everything to Lutron Radio Ra or equivalent. 1 button to control a room is very nice vs 6 or 8 switches. 1 button to turn on/off a house is even better.
Be very award of LED lighting colour temperatures, make sure all lighting matches and is a colour that you like.
I try to convince clients to be realistic with their budgets, don't skimp on whats inside a wall, just to afford a fancy window shade. Put your money where it can't be easily replaced later. If necessary dont finish rooms and backoff on the number of bathrooms. It's comical (sad?) how many 5 bathroom homes only use 2 of them.
Pantry and easily accessible storage is hugely beneficial to the useage of a home.
Kitchen - pay attention to counter heights. We almost always build them an inch or so higher then normal. Unless there is a tiny lady in the house, most people prefer it.
Also look at height to the upper cupboard, base this off of what kitchen appliance you keep and use on the counter. We are generally 2"-6" higher then standard and zero complaints, everyone loves it. Unless you love a specific backsplash. Consider paint. Saves a bunch of money and really isn’t hard to keep clean and looks great.
Skip the crazy multihead showers, 2 or 3 is enough. Same with steam showers. Virtually no one uses them. Same with fancy coloured lights or built in stereo, no one uses them, and the few who do, know it before they build.
There are alot of options available now on homes. Honestly, if a salesman brings something up that you or your wife never thought of, then as good as the idea sounds, you'll probably never utilize it. Approach all the fancy additions with care, its an amazing way to blow budgets very quickly.
Take a serious look at Solar. Even if you choose not to go with it today, wire for it. I have several clients who put money in their pockets every month after about 5 years and the systems are only getting cheaper and more efficient.
Shower pan in the garage or outside with hot/cold water and a spray wand.
Make garages wider/longer then standard.
Have fun with the process.