Lots of good suggestions have already been posted. Here are a couple I don't think anyone has mentioned... Lights in our walk-in closets will be wired to door switches so that the light comes on automatically when you open the door and goes out automatically when you close the door - like a refrigerator light. I'm hoping this set-up will also help me train DH to CLOSE his closet door instead of leaving it standing open all the time! Several outlets in the soffits way around the house for plugging in Christmas lights - all are wired to a single switch for ease in turning lights on/off. Extra lights in our stick-built attic space with a switch by the access door so we don't have to use flashlights to find stuff stored up there. Everyplace I've ever lived had one light in the attic at most. Even with it on, the thing you're looking for is always in some other corner that is dark. Mirror defoggers in the bathrooms (a very inexpensive luxury!) Outdoor lights specially positioned for reading when one is sitting on our porch swing. A floodlight positioned to shine up and into the stained glass window that is in our the stairwell so we can enjoy it at night. Lots of extra electrical outlets around the exterior of the house.

Are you sure the aforementioned 2x4 "on edge" is not just a ceiling joist, perhaps sitting on top of a normal top plate? Otherwise, the whole interior wall would be only 1.5" thick--does happen occasionally for partition walls where space is at a premium.... But more often, the partition wall really is 3.5" thick and it was put in during a remodel where they did not bother to cut through the ceiling drywall... so you do not actually see the top plate from the attic.

"A better time to go over things is when the house is framed." I agree. Ask them to do a walk through with you when the house is framed. What we do is a full walk through, room by room. Make sure you think about anything and everything you might want. Outlets in your soffits for Christmas lights, under cabinet lights, over cabinet lights, where you want switches, outlets for all your TV's, how many cans you want, how you want them layed out, anything you might want outside, anything special you want in the garage, etc... Try to have as much information as possible too just in case your general contractor doesn't, like your cabinet lay out, vanity heights, if your jetted tub has a heater, etc... If you have a good electrician they will ask questions and give suggestions. If you're having someone do all your low voltage (TV, phone, network, etc...) make sure they and the electrician are on the same page also. Having them wire for a TV, but not having a outlet close by for it, can be an expensive fix. Pretty much they can wire for anything in the world you think you might want, hell we've even wired heated toilets that spray perfume and dry you off after you've done your business. But make sure you take the time to think about everything you want. Every change you add = extra $$$ and it adds up quick.

I was going to suggest going off grid electric, but given the power demands for the hobbies, that is a lot of panels. Still, I'd do the calculations. Is that a good wind area? If you can do it, you might flip David's suggestion of one utility around. Going back at least a decade, there are plenty of people out there that got disgusted with the cost of brining in electricity and went off grid instead. If you have nat gat, genset manufacturers have finally come around to making DC gensets for that application. (You really need a generator to equalize batteries by my understanding. That may well be, however, for flooded cell batteries only.) How come 3 ph is not a better way than single? You'd get 50% more power adding a third conductor of the same size. If you can get the POCO to give you 3 ph open delta, you can have 3 ph and 240V. That said,as Mike pointed out, with the cost of VFDs so low, what's the point? I was shocked when I looked at costs online a few months back. Note that you have to be careful about how the utility bills other than residential 124/240 too. The local utilities commission regulates that and some make sure that commercial and industrial users pay more by charging lots more/kWh for anything 3 phase. If you build efficiently, your costs other than the shop, hobby and domestic hot water can be be nil. Tankless and recirc seems like a weird match to me. You have a system that provides hot water on demand so you have no standby losses, then you connect it to a system with standby losses. Is the recirc going to be on a timer or controlled with occupancy sensors? If I have gas and need a new water heater, I'd buy a Westinghouse WGR060NG076 or larger tank and never look back. That goes especially with hard water unless you plan to install a water softener. Have you done the well research yet or maybe drilled already? I'd go with induction for your cooking hobs if you want easy clean-up. There is nothing easier. If you are not sure about it, buy a plug-in unit and see if you like it. You may save a lot of AC costs in addition to the straight savings at the cooktop. Ideally, I'd like one resistance hob for simmering. They suffer from the same drawbacks of the duty-cycle controlled power output as thermostatic resistance heating devices. I don't know if inverter powered induction is theoretically possible or practical as it is for microwave ovens, but it might work well if it is.