Thank you for the responses, Yeary2 and Murray!
I am really serious about the decision I'll make, whatever it is.. it's a scary step to take and I don't want to jump out of the frying pan and right into the fire.
The risk of depreciation is definitely one of the largest concerns for me. My fiance and I are planning to talk with a few realtors about land in the area (we're new here) because I know that the house will almost certainly depreciate in value. Because of that, and because this area is growing very rapidly, I want to get a nice piece of land that I'm resonably confident will go up in value and can be subdivided and sold in the future.
If we decided on a Fleetwood modular it would be a long term home. I'm in a unique sort of situation in that I hobby breed small parrots. I would love to expand and build some outdoor aviaries, which are usually pretty permanent or don't knock down easily. Moving is very stressful on the birds, so I would rather pick a long term home that is large enough to accommodate everyone, including possibly planning for children in the future.
At this point, I'm very wary about committing to this house. I think the next step for us will involve a factory tour since so much can hinge on the individual factory, as well as getting some references from our dealer. I would also like to talk to some contractors, or even inspectors that can give me an unbiased opinion of this specific factory's work. I'm generally not a very hard-nosed person, but I think this is something that I need to be a little pushier and firmer about than normal.
Murray, my dealer does welcome my questions, but sometimes I get the feeling that they're not used to them being asked. It's not that they don't want to answer the questions.. just kind of like they haven't had anyone bother to ask them before. And the gentleman from Fleetwood, that I did a conference call with, had just started working with them so he was double-checking everything with (I'm guessing) his supervisor.
Thank you for the information about Energy Star, too. (Sadly, the company that has so many compliant homes is the one company that make me incredibly uncomfortable with their sales pitches.) On the Fleetwood invoice quote I have these Energy Star upgrades are listed, but there is no explanation about what each one entails:
Energy Star-Climate ZN 2 $2,495
Energy Star-Climate ZN 3 $975
Energy Star-Climate ZN 4 $495
The modular code upgrade includes 6:12 roof pitch, architectural shingles, and R30-13-19 insulation. Their website claims that floors are framed with 2x8s, but I believe the modular upgrade includes 2x10s.
I want to take a huge list of questions with me on the factory tour (that's assuming they give them), so I hope they're ready. Ha ha. Some of my big concerns right now are the type of studs in the exterior and interior walls (2x6, 2x4, etc), warranty coverage, rechecking whether or not OSB floors are actually part of the modular package or not, and what the Energy Star packages offer. I think a wise decision would be to get everything they say will be included in writing, too, in case a complaint ever did have to be filed.
If we DID opt for the Energy Star package (not sure what our zone is), what all will that inspector check before the house passes inspection? I would rest a little easier if that included the wall studs and such, since so many things are out of sight once the sheetrock goes up. And don't modulars have to meet local stick-built codes? Would Fleetwood decide who did that inspection?
Phew, sorry for such a long-winded post. Trying to be thorough.

I do think I'll be picking up a book, and I will check out that report on housing locations. If anyone has any suggestions on specific things to look for/ask about I would love to add them to my list.
Nikki