Rob, its very tricky to comment on pricing because there can be so many variables. Is $9200 high for 2 patio doors? If they are stock size, 6' doors with a simple install and little to no upgrades, yeah, that would be on the high side. That said, it looks like 1) is a 3 panel unit which can bump a standard 2 panel price by 50% give or take, and despite the fact that one appears to be "average" size, ordering a custom size literally a couple inches different can have a profound effect as well. IE: "average size" and "stock size" can be close on a tape measure, but not on the wallet. Then of course you have the installation circumstances, product and installer quality, etc... If we subtract the door cost and assess only the windows, they come out to roughly $640 each. That puts things in a little better perspective in trying to understand the situation. If we are considering a quality window installed by a reputable company with a good history, that price is very fair, if not aggressive on a per window basis. Again though, many variables regarding where exactly that falls on the spectrum.... The good news, is that I have some very decisive advice as well. One of the frequent and respected contributors to the forum here is Windows on Washington, and I believe that they they serve your area in NoVa. I'd highly recommend talking to them, as I know that you will get a very fair price on a high end window and installation. Obviously I think doing business with them would be wise, but if nothing else, you know what you are getting in their quote for comparison purposes. I've know the folks over there for several years and they are truly top notch.

We just went through very much the same design question. Back of our house has greatroom, kitchen, and morning room in a L. Greatroom is 20'4", leading out to deck/lake. Originally stained double doors and bank of 2-3 windows on each side. Looked very classy. We looked then at the Western corner slider because we love the seamless look (https://westernwindowsystems.com/multi-slide-door-systems/series-600-multi-slide-aluminum/). Turns out there's a lot of cost for the doors, and the engineering associated because of the removal of the corner. So we ended up doing 1 long slider and 1 shorter slider meeting at the corner. How this is related to your question is the long slider. We had options of doing 4x4' like you, but ended up doing 3x5'. Mainly because we wanted the doors to stack to one side, rather than open in the middle. 4 panel would be more room lost on the interior of the house. Originally we were going to do a pocket, but there wasn't enough room on the wall for 3x5' + pocket, so now we are doing one stationary panel but it will open to 10'. From a design perspective, I have to admit that the house looks different from the outside. I love the view out it gives, but it was a bit jarring with the craftsman/sized windows we had specified. Have you looked at a 3D model to see how the sliders flow with your architecture? Oh and be sure to check how much the bug screen is. The bug screen for a Western Windows 3x15x8 was almost $2,000! :/

I've not generally been a huge fan of wood/vinyl combo products, but the Aeris is actually fairly compelling, particularly for a wood interior window, prefinished, at a decent price point. I think that you would be happy with that choice... Regarding double vs triple pane, its relative. Is it less important in your area than in a cold climate like here in WI? Certainly. That said, even a triple pane window will only be a fraction of the thermal performance of your walls. If you do a fair amount of conditioning of your interior air (either heating or cooling), you would not be crazy for choosing it at all if budget allows. If otoh you have you windows open 350 days per year, then why bother ;)

Update - After talking with the local lumber yard that sells most of the sliding glass doors to our local contractors, contacting the brands mentioned above and getting 4 estimates I have finally ordered my new door! Estimates ran from $5k for a substandard product that a local window company tried to convince me was as good as any of the other brands, but substantially lower priced. ( VyWinco didn't have such hot reviews) to 16k for an Anderson 200 series door. Funny thing is, I ended up with an Anderson 200 series door but from a GC/builder vs a windows only shop. He quoted me 8k for the same door as the 16k door. The local Softlite contact told me they no longer make a 4 panel door and recommended Paragigm. Reviews seemed to suggest that they were great doors, but were sold and the quality suffered. That estimate was over 7k and I wasn't going to take a chance for less than $1k in savings. I felt very comfortable with the GC, who measured things, discussed options, researched a few different doors including Marvin and recommended the Anderson door. He pointed out the other other door that I have is the same as the one he is recommending and the two will match. I like the other door (now 15 years old with no issues). If he does good work I may hire him for other projects. Thank you to everyone who helped me make this decision.