Wow! Super lucky to have the luxury of extra space! I can't tell you what to do exactly with your space, but I would suggest to change out your garage door. I love this idea, and I would really like to utilize it when I build! If I can't have it...I'll just be happy that someone else is enjoying it in the meantime!

Love the door do you have a web site??

Unless you have a very beautiful garage door I would paint it a color that blends with the brick IMO they are all too much in your face as is I loved it when the garage was at the back of the house not front and center

There are discrepancies between the two plans you have provided, so it is difficult to understand what has been built and what is proposed. That being said, the powder room will have more of an impact on the garage space than you are indicating, and think that will have negative impacts on the garage which you will want to avoid. The location by the dining room and stairs will also require significant changes to the plan in that area (powder room is still represented too small). The powder room adjacent to the pantry seems like a great place to put it, or in the ancillary seating space to the right of the main living seating. That seating area does not seem to have a great functional importance except to have the dining/living/side living space extend across the whole house, unless there is something happening that isn't apparent from the plan view alone.