Cheap windows may have similar performance figures when they are new, but my understanding is that they don't last very long. You're then faced with replacing the windows some years down the road. We went with Marvin wood/Ultrex, and love them. I put a cheap vinyl window in the garage, and the difference is astounding. The Marvin windows weigh about 3 times what the vinyl one does. I also wanted a paintable exterior on the windows, as I wanted a different color (of course!) than is available from the factory.

I guess a lot of these decisions depend partly upon how long you plan to stay in the house. Many people move a lot, and some upgrades won't pay off that quickly. We move very infrequently, and the house we are building should be our last, with any luck. We only have this one chance to get it right, so I'm putting a lot of effort into a strong, tight, low maintenance envelope, with money being saved by cutting back on frills that aren't needed, or could be added later. I put our Hardi siding over a rain screen, as the paint is supposed to last a lot longer that way.

Good thoughts from MushCreek. Its tough when youre working with a builder or subs outside of their comfort zone but youre smart for doing the good research and I think it would be good to educate them and perhaps do it in a way that lets them know they will be better prepared for the newer energy and performance codes by learning from your project.

For foam sheathing, have you considered Huber Zip+R? The regular Zip seems to be widely adopted and its not much harder for framers to upgrade to the Zip + R for much better performance. Its much easier to work with than typical foam sheathing and gives you the airtightness of the tried and true huber zip system. It installs almost as easily as regular structural sheathing.

As for windows, I suggest visiting 2-3 supplier showrooms and getting quotes for different lines and products. Sounds like your project would benefit from some passive solar glazing on the southeast but if not, at least get windows that meet the 2012 IECC minimums: .35 or less Ufactor and .25 or less SHGC. I strongly suggest going lower on the Ufactor if you can.

Take your quotes and window brands/material options to the windows forum. Very helpful and knowledgable folks there. The Integrity is very well respected but there are vinyls out there that could outperform them for less $.

Sounds like a tough road to get a true rainscreen included but you should do it if youre installing any real wood. You could use good ole vinyl siding, without the integral insulation backed products, it forms its own rainscreen. Or just go with Tyvek drainwrap/stuccowrap for behind composite/engineered siding options.

Since you havent mentioned it, try to get a third party to blower door test your home and do your best to get good results. This is the area of energy performance that needs dramatic improvement in our current construction industry. When building new, its one of the most affordable improvements one can make to the building envelope that effects durability, indoor air quality and energy use.

what are your questions?

spray foam insulation may be the 'rage' but
foam in walls has a long payback for something
we can do without the cost of foam.
foam sheathing boards on exterior of the
zip system mentioned above. personally I don't
see that product in my area, but Brian can certainly
advise you on it.
goal is to make wall air tight.
air tight from outside with foam sheathing..
conventional insulation in wall stud bays,
and air tight drywall to interior.
google ADA for details to share with builder &
sheetrock installers.

focus on penetrations in ceilings & make sure
they are sealed up. use products that last not
cans of great stuff that will shrink over time.

location of hvac system & ductwork is unknown to us.
please supply info. type of hvac system etc.

maybe you should hire your own personal energy
rater. they can advise you on each step of the
project & in planning stages it is easier than ever
to incorperate these upgrades.
the rater should have local resources that they
have worked with sucessfully in the past.
they can also advise you on brands of windows
local to you. for the mininal cost of the energy rating
that includes advise specific to you and blower
door & duct testing..its a win win for you.

best of luck & good for you asking questions in design stage.

Any recommendations in Oklahoma?

energy rater, what are "products that last" as opposed to great stuff?

backer rods & caulk with a long life are the best
tried and true products. backer rod is for gaps
over 1/4", backer rod is pushed into gap &
caulked on both sides of backer rod to window &
wood framing. for large gaps let first pass of caulk
dry completely, then caulk over it. caulk will shrink
when wet to dry, so making a second pass is the
best application. after all...youwon't easily get
to these areas again.
I like dap's Alex caulk minimum 35 year life...but
as high as 50 year. I also like the clear caulk.
goes on white & dries clear in 24ish hours.
so you can see where you left off!

bet of luck.