Typo? 36"of Pink Panther would be over R-100!

That trick sex in the shower gonna get you hurt!

I didn't build mine but bought it a year after it was custom built. What I love that the builder did:
Spray foam everywhere
All LED lighting everywhere inside and out
Tinted windows all around (makes a huge difference combo'd with the spray foam)
NG instant hot water heater
HUGE shop (40' x 50') - I would have done more electrical in it, but the panel has the capacity to do more. He also added water and a toilet too, so that's a huge bonus.
Deep back porch that is shaded all day long - makes for a great place to hang out even in August heat!
Saltwater pool (my addition after buying the house - LOVE IT)
Cat5/6 and HDMI outlets in all rooms
Security Cameras all around
Long/wide driveway that I can turn around in easily

What I would add - emergency backup generator. This is next on my project list and probably the last thing I want/need beside to finish insulating my shop. You can at least at the transfer switch now and then run a portable generator in emergencies at a minimum to power what you need.

I just got through building one. Where I live we don’t have natural gas. We use propane. I wish I would have piped for gas everywhere. And quick connection points on my porch for a grill if needed and for a dryer. Insulation is cheap. Buy as much as you can. If you build a bench in your shower make sure the tile guy builds it out of block and brick. No wood. And if your like most guys you don’t need as big of a closet as your wife. However build it just as big as hers and make yours like a safe. Build it with fire proofing and solid steel centered doors. It’s a little more money but knowing what your family really cares about it safe for a short term fire is priceless. I did this and my closet is full of class pictures drawings birthday cards. It wouldn’t be the end of the world if we lost all that. But in the event we have a fire hopefully we will still have that little bit of memories. And I got to tell you a sink on your back porch with hot and cold water is priceless.

Most have already been said probably but....

Cat 6 cables ran to every room, safe room, 10’ wide garage doors atleast if using singles, go ahead and install a transfer switch for generator, under ground gutters if needed, and large pvc pipe under sidewalk or drive for future use. We added insulation in some interior walls for sound deadening. After electrical and plumbing is roughed in, but before Sheetrock go through and video and take pictures for future reference. This has came in handy a lot. I also put plywood behind the Sheetrock on a wall that I planned on hanging deer heads on, allows me to move them around without a stud. Prewire for security cameras. We installed a floodlight switch behind the night stand at the bed...easy access to switch on at night. Large living room, decent size pantry and closets were big on our list.