Is It a custom home or a developement? I am a general contractor Alex. If the job is production it will usually be plumb and level but slapped together. If it is an independent builder it might be tighter work a little extra cement in the foundation ect.Be there the day they pour the slab and make sure they pull the rebar up into the slab(lots of times the finishers just smash the rebar into the dirt). a couple of guys should be walking around with hooks pulling the rebar up.The crew should be working the cement into the footing with either vibrating equipment or serious manual prodding. Make sure they are not faking it. Check the walls for firmness around entry doors. If they are shaky the door movement will crack all the surrounding building components and the house will feel cheap.Make sure the put blocks in the walls where all built-ins go, especially kitchen cabinets. Make sure the attic is ventilated properly. Tighten the anchor bolts again right before drywall. The wood plates shrink and the bolts will be loose. If he has an option for copper pipes and sprinkler system he should put that in. I guess plastic pipes are used pretty regularly now for potable water and sprinklers. The stuff normally used for sprinklers is going to get brittle and crack in a few years time and people will be turning the sprinkler sytems off. I paid $1,500 extra for all copper in the sprinkler system. tell them to install back wired commercial grade receptacles and switches.Put in a hot water return line from the furthest fixture to the water heater and insulate it or else it will take forever to get hot water there. Forget about this if it is going to have a tankless water heater. Keep a very close eye on any water proofing work interior showers,bathroom floors over wood, and around chimneys windows doors balconies ect. Also install rain gutters immediately. Rain gutters and drainage away from the house are the most important elements in a house aging well.use the highest quality roofing underlayment and maybe have them double it. Do not do a code minimum on this item. Don’t let anyone tile to drywall or plywood anywhere.Make sure they put a slip sheet over any “drying cracks” in the foundation where tile goes.