Just trying to help since I've done more than a few of them and can share my experiences. The main panel will obviously have to be relocated since they are not allowed to be mounted in a clothes closet. This could be a pita depending on the budget of the job (and that's a big question mark in most cases). It may be as simple as reversing the direction of the panel from inside the closet to facing into one of the rooms on the first floor (assuming there's no basement).
To save money on labor and material, a 2nd floor sub-panel in the new addition makes sense. Usually 100 AMP, 20 circuit panel. Then the only wire you'll have to run to the old panel is the SER from the sub to the main.
From there you'll need approximately 1000' of 14/2 for receptacles and lighting circuits, 250' of 12/2 for your bathroom GFCI's, boxes, staples, wirenuts, ceiling fan braces, bathfans, 250' of 14/3 for smoke detectors and 3-way/ 4-way lighting, nailplates, radio and a good attitude and you're good to go!
For lunch I like italian sub-sandwiches with lettuce, onion, tomatoe, light on the mayo and just a little oil and vinegar so it doesn't soak the bread.
Do you mind working late? Because we got 8 other jobs just like this one and people are waiting on us to get there.