TC, the two rooms you mention often have some vents working against you; your clothes dryer vent and many times a range hood. Dryer vents are notorious for not sealing well; check the outlet on the outside of the house and see if the vent flap isn't closing because of lint build-up.
Also, both these rooms often have plumbing that is in exterior walls; check your kitchen sink cabinet to see if you have air flowing into the cabinet from around the drains and water pipes. The same goes for your laundry.
These are the items most likely to be the cause for your frustration.