@ Swanky, that's a very tricky question to ask someone who won't be living in the house, because tastes are a bit different when it comes to personal space.All the same I'll try answering you based on discussions i have had with many homeowners that i have dealt with.
A house in the range of 2200 to 2600 sq ft should be able to give you sizeable airy rooms and also leave enough land to have a walk around garden....plant one or two trees and have area for having a barbeque....
The trick in building houses nowadays is to provide space and air in the house...large big windows to bring in as much light as possible, enough compound on the outside for kids to play and for relaxation, one or two trees here and there for shade, flower garden to make it homely. That's the reason why you see in many property adverts, vendors specifying that the property has mature garden and putting a high price on it....
Anyway, hope this helps...feel free to seek further clarification.
@Longman, i have a contact for someone who has experience in the tech and owns the hydraform machine..0722-393187 Rapando.