Master closet: Our bedroom is downstairs, and surprise: there are no closest! Actually, there are no closest in most of the house, so this will serve as our linen closet as well as.
Master bath: The current bathroom is upstairs, and only has a bathtub because of the sloped ceilings. People look at me weird when I say I haven't had a shower in 2 years

Half bath: The original plan had the master bath with two doors, but I wasn't a fan of a 'Jack and Jill' style bath, and as a guest in other people's houses I find it a bit weird to use the master bath. The powder room gives us a bathroom on the main floor of the house as well as one close to the outside (without tracking mud through the house!)
Laundry room: Currently our washing machine is in the kitchen pantry, and the dryer is in the unheated attached shed (which makes it hard to dry things in the middle of winter). We have a full refrigerator, so once the washer is moved out of the kitchen we can finally have a freezer!
Stairs: There will be stairs to the upstairs and basement. The existing stairs to the basement are under a sketchy floor hatch in the current attached garage.
Upstairs: This isn't shown because it's not very exiting. This will be a rec-room type area for entertaining, children, etc...
Basement: Also not shown, but there will be the modern equivalent to exterior cellar doors so we can toss wood in.
Here is the plan for the outside. Right now the house is covered with fake brick material and metal siding, which will be removed and replaced with the same wood siding that will be on the addition.