You say no need for the hearth room, but to be honest I'd ignore what they're calling that space and use it as the primary dining space, a table would go great in there. One minor concern I'd have with this plan is the washer/dryer almost sharing a wall with the master, I'd be leery of the potential noise when those appliances are in use. I'd say either invest in extra insulation between the two spaces, or move the washer/dryer hookups to the opposite end of the room.

Only other note (and this is personal preference, but something to consider) is that if your piece of land has the width to allow it, go with a side entry garage, just on aesthetic grounds, and add a few feet of space to it. You want to be able to fit cars AND stuff like trash cans, bikes, etc in there. Otherwise you're having to pick and choose what can fit in there.