I think your insulation choice for your climate is decent. I would not waste your money on foam. Spring on the small amount for the ZIP to help tighten things up some. If you are putting all ducting in the crawlspace, treat that space similar to your house on a sealed, insulated level.
For consideration on costs, you need to factor in your electric rates with efficiency of the units (COP). They will range from 3.5-possibly over 5 for the Waterfurnace. remember, these are unit numbers. They do not factor in energy running pumps and other items. The 5 turns into a 3 really fast. However they should still be better then either of your ASHP options. being as the prices, after credits, equals out to be the same, you need to look at financing numbers as well. If you plan on financing the entire 48k, you still have that for the life of the mortgage. What I have done in the past was to work with the bank. Get a 2nd, either personal loan, line of credit, or 2nd 5 year or less 2nd mortgage for the estimated amount of the credit rebate. Assuming you can claim the entire credit, once that is returned to you, you pay off the line of credit and are left with the 24k financed on your mortgage.
Also check with your local utility company. Ones in our area have good incentives for geo systems. We can get about 5k in addition to gov credits on a geo system for example.
If you have the land space, save the money and go with the horizontal wells.

I'm not an expert but I can tell you what we chose to do. We are in CT so our climate considerations are a little different. Our house is also significantly smaller than yours. We have 2100 sq ft on the main level and finished off about half of the lower level (basement) which is full walk out....home is built into a southern facing slope for passive solar gain and we put 5kw of active solar panels on the roof. We have a full attic above which we did not insulate but chose instead to insulate at the attic floor.

We went with closed cell spray foam insulation. All the research we did on going green said to put your money into insulation as, no matter how you generate a BTU, the longer you hang onto it, the better off you will be. It adds structural rigidity to the building, is waterproof and air impermeable so you need no extra vapor barrier. We also insulated under the lower level floor. We put all of our ductwork in that conditioned lower level space. The lower level maintains 63 degrees all winter without heat (temp rises to 67 degrees on sunny days due to passive solar gain from souther exposure).

We went with Econar geothermal and we have two 250' vertical wells which were drilled in one day. We have a lot of land, but went vertical as it was faster, less disruptive to the land and we have lots of rock in CT, plus we had constraints of wetlands (and the wetlands people can be real bugbears about stuff.) It does a great job of heating and cooling. The system was designed to handle both levels, but we have really only used it for the main level. We have never had to turn on the emergency backup heat. It is also great not having the ugly, noisy outside air compressors required with standard systems. And here in the Northeast, we love waving at oil trucks as they don't stop at our house.

With the tax credits, the geothermal has paid back immediately.

In our area, why wouldn't you go horizontal if you have the room? Wouldn't horizontal be less pumping and therefore more efficient?

If you have ducts in the crawlspace, there is no significant benefit to a radiant barrier. I know it is cheap but it still doesn't pay off. Better to add some r-value to the attic.

It isn't that significant but you would do better with 2x4 walls and rigid foam sheathing. It may cost less also.

Once you have geo and a reasonable envelope, it is all about the windows and shade trees. If your view can be south you won't pay much anyway.

Progress energy gives 5% off for life for Energy star certification.

Progress energy gives 5% off for life for Energy star certification.

David - Where are you finding this information? I can't locate it on their website and we only got a cash back incentive not a for life incentive. I have seen you mention this before, but I just figure you had a different electric provider.

Wow... If I could get the same quote as you for #3 in my area I would be jumping on it!

Maybe they changed it. Both Progress energy and PSNC gave us 5% discount for life. These things obviously change and this was 3 years ago.

Generally though, Progress Energy only seems to be adding to the incentives. We got a solar hot water payment after the fact and now they have a solar PV incentive which is cash upfront. But maybe they are focusing on cash back incentives nowadays.

Momto....have you thought about going with ICF? On the geo, you might want to read the thread I started over on greenbuildingtalk.com titled 'Why is geo so expensive?' It was back in Nov. I hate to say it but a majority of contractors installing geo are basically ripping people off because it's 'new' and 'green'!! That 3rd quote you rec is reasonable. Are you the O/B? If so, you need to make sure you are getting GC pricing and NOT consumer pricing on everything!

robin0919 - great tip. Any suggestions on finding a reasonably priced contractor, I'm in California and have received quotes for twice that!

Laura, go to that web site. There are good contractors on there all over the place. Post asking if they can recommend one in your area. Is your area union like is in the NE?

Laura, were you able to find that thread? There is ALLOT of good info on there. It's a long thread.

Robin, you referred to a a thread and a website, but I'm not sure what you mean.

I have only been able to find a few contractors in my area, but I may start a thread about it once we get more towards that stage.

I have a question about the tax credits you are getting... They seem to take your cost down to 1/2! I thought it was only 30%. Do you have some state credits?

Wish I could find those costs in the PNW. Would love to do geothermal instead of ductless, but it seems WAY too expensive here (our local "credit" is only 1500--and it is a utility credit).

Yes... NC has a 35% tax credit up to $8400, so this helps the numbers tremendously. Fortunately ( or unfortunately), we will be able to use the max of the credit. There are also some small paybacks from the energy company. I hope you can find some similar incentives. We certainly wouldn't be doing it if the cost was not so close to traditional.

Momto3kiddos - I'd say fortunately. We are in NC and we won't be able to use any of the state credit.

Ah, I just looked at the after tax cost without taking into consideration how much the tax savings actually was.

With that extra state incentive it makes it really quite reasonable!

Laura, go to the web site greenbuildingtalk.com then go into the 'geo' forum. The thread I posted back in Nov was titled 'Why does geo cost sooo much'. It's a very long thread and has allot of good info for anyone interested in geo.

http://www.greenbuildingtalk.com/Forums/tabid/53/aff/13/aft/79495/afv/topic/Default.aspx