^All of those are good except the angled wood/tile one. That's highly subjective to what a particular person finds appealing.
- insulation, get the highest R value you can afford. Once it's in the walls you''re stuck with it.
- run network cable throughout the house. Bedrooms, kitchen, livingrooms. Wireless may be more convenient to use, but it's still not as good a connection as plugging in. Plus, it gives you more options on where to plug in those wireless routers and thus eliminate areas with poor signal strength.
Start watching Holmes on Homes
on hgtv. The show will give you lots of ideas on what to look out for. Heck, watch lots of hgtv and DIY tv in general. You'll learn lots of stuff about how houses are put together in general.