I am in the process of building my final home. One thing we stipulated with the contractor is to install a recirculating hot water pump that is thermostat controlled and thermally insulate all the hot water lines. The pump will recirculate the water when it gets below a set temp and each outlet has immediately hot water. Much cheaper than placing on demand water heaters at each outlet. Fully insulate all internal walls for sound absorption, it doesnt cost that much and makes for a much quieter home. Put plenty of outdoor faucets so you dont have to pull 100 foot of hose all around the house for watering plants or washing down the patio porches. Install receptacles in soffits for Christmas lights (no power cords running all over the ground) Go for the lowest SEER rating on the HVAC that you can afford to save on electrical cost. THe wife insisted on have kitchen appliance garages in the cabinets to keep her electrical helpers out of sight but still not have to lug them from under the cabinets to use them. Dont swing your doors so that the swings overlap so that one door will bang against another when opening, and make them 36" wide wherever possible for ADA compliant. I used all double hung windows so they can be cleaned inside and out from inside the house. This is also good for ventilation by opening the top of the window to allow the hot air out can reduce AC needs. Stay away from sliding doors for patios, etc. as most of them become hard to open after the bearings start going bad and dirt builds up in the tracts. which is hard to keep cleaned too. For eave overhang go with 16" or more to keep more of the elements off your house walls. Lots of plans will only call for 12" eave overhang. If you want to conserve dollars, limit the number of gables in your home. The dollars needed to install a gable for aesthetic reasons adds up to big money quickly. If putting sheet rock inside your house, consider putting in rounded outside corner moulds rather than square. They hold the paint better. Shop the internet for bargains on plumbing valves. I saved $800 on one shower faucet compared to the Big L box store price for the same brand and type and got 2 additional body shower nozzles to boot. Dont use the Chinese made sheetrock as many houses built in 2006 in the Southeast have had to be torn down to get the contamination cleaned up (check articles online).
Buy many of your high dollar items ahead of time when you find them on sale. I found the double wall ovens and range on sale and got the 5 year extended warranty to boot for less than half the regular selling price.
Depending on your location, you can save big bucks on flooring by buying from lnational iquidators rather than the local supplier even after paying extra for shipping. I found my stone flooring in Houston and had it shipped to Hot Springs Ark for less than half of what it would have cost in Ark. If trying to buy online, always get a sample, it doesnt ever look like the photos.