Custom home

Here are some really good ideas for building your custom home:
Talk with an interior designer. They may have some really good ideas about things you like or want. Easy to build in, more difficult to put in after construction is nearly complete.
Talk with your builder. Take their advice. Be up front, but firm with what you want and flexible in other areas.
Get it in writing. Dates, commitments, you name it. And don't pay until you're happy with the end product. It's your money and you have to live with it.
Don't over-estimate how much work you can do (like wood floors for example) and don't over-estimate your skill. If I could do it all over again, I would hire all of the work I did myself and be much happier paying for it.
Get top of the line HVAC units.
I recommend this spray-on expanding foam insulation.
Double check all electrical connections are in place for septic systems, outside lights etc., in your island, hot water heater closet and HVAC unit locations. Check this before the drywall goes up. If you have an island or floor plug, it needs to be checked before the slab is poured and after to make sure their conduit didn't collapse. Two might be a really good idea in this case.
Drywall and trim shrink any openings you may have left for a china cupboard, buffet and/or hutch. Leave extra room in the blueprint for it. Measure during framing to make sure the opening is big enough for your furniture after the wall and trim are installed.
Get a working model or a picture of what you want. If you can see it, touch it, feel it and you like it, that's good. If you think you know what it's going to look/feel like, it's not going to look like that.
Get a can of spray paint after the electrician roughs in your outlets and switches. On the floor near each one, paint a symbol for wall switch, single/dual gang outlets, fixtures, any opening in the wall. After the dry wall goes up, make sure you have a hole in it for each of your marks on the floor.
If you have nailed-down wood floor, be sure to leave 1/4 to 1/2 inch gap between the planks and the walls, all the way around. Otherwise, your floor will buckle when it absorbs moisture from the air. No matter how good it looks once you just finish installing it. And I would avoid the pre-finished stuff and just have it sanded. This stuff cups too much for my liking.
Make sure the painter covers the floor in any areas where you will be laying tile.
Install a central vacuum system. It's the absolute best decision I made concerning the house.
Put some bar lights over the vanities in the bath room.
Don't use these incandescant can lights as the only light in a room. When they get hot and click off, the room is dark.
If you have a freezer, make sure the electrician knows where it will be plugged in and don't put it on a Ground Fault Circuit (GFI/GFCI).
Try to get a sample of the exhaust fan you'll have in the bath room. If it's noisy in the showroom, it'll be noisy in your home.