Love having a small family room adjacent to / part of the kitchen. We put a gate across the entrance to the kitchen, but DD could play in the family room while we cooked and cleaned. She still felt included (very social kid) as we could still chat together and we knew she was safe. She had one shelf of toys there, so it wasn't as if the whole area became a permanent kid zone of mess.
I prefer having the laundry on the first floor, close to the kitchen. With it located there I can hear when the washer and dryer are done. I also prefer to fold at the kitchen counter, as it is easier on my back.
We do have a fenced back yard, but I don't think DD played out there alone much until she was 3 or so. She was probably 2 or 3 before she would play in the playroom alone, too. If you are going to be a SAHM, I think it is helpful to have different rooms or zones for play. It somehow breaks up the day and can reignite their interest.
A handsprayer in the tub is really nice to have. Makes it easier to clean the tub, but is also nice for washing hair. I think ours actually came from the pet store, as we had it for the dog long before DD joined the world, but it is an inexpensive item that makes life easier. If you don't mind spending more, you can get a nicer one like this:
http://www.amazon.com/Speakman-VS-223032-Anystream-Refresh-Polished/dp/B0054ANVKC/ref=sr_1_14?ie=UTF8&qid=1336668096&sr=8-14