Is the floor plan really so bad that we should start completely from scratch?
Yes, as Thies (11ant) already said, with a blank sheet in front of you, you are less likely to make the same mistakes again.
Just post the site plan in the thread so people can get an idea of it.
A bay window is a nice feature in the right place. But it is also expensive. You are also planning with a basement and a double garage – can we assume that 750K will be spent here? If yes, then get a real architect for the plan – not some planner without a plan. Once the floor plan is set, you can still change.
Apart from that, do you really want an office in the basement for client visits? Wouldn't it be more pleasant if they didn't have to walk through the private living area – meaning they would have an entrance from outside?