Like Ryano said banks sometimes have heartache about loaning money on an already started construction project. If they are not already involved do it now. We insulated all of our interior walls and the first floor ceiling to help with noise. I guess it helped but we have 3 kids so I would hate to hear how loud it would be without it.

Make sure any room with an exterior wall gets an HVAC vent, even if its a closet. My first HVAC guy said that was not in his price (along with a bunch of other stuff), so another guy ended up doing mine.

When I built mine I had 2 service legs run to the house. I can't remember if a standard leg is 150amps or 200, but either way I have 2. It made adding a shop and pool super easy.

Any walkway that is not a cased door opening we used bullnose corners for the sheetrock. To me it looks good and minimizes the square corners that are so easy to scratch and chip.

If you are using the attic for storage or have a craft room/storage room upstairs definitely look into a versalift or something similar. I didn't hear about them until about a year ago. My wife has a storage/craft room above our carport and I really wish I had put one of these in when we built.