OK .. well first a couple things about your project .. adding more spaces will not add any more amperage capacity, it just adds more spaces. You will still have only 200 amps to your house.
Why do you say the electric company is running more wires to the meter .. are you also having the main service upgraded??
How many runs are there to be made from this new panel?
How far is it from the new panel to the area where the circuits will be used?
Are the walls open from the new panel to that area?
You may not need more amperage, what appliances do you have? electric heat, water heater, hot tub or spa, central A/C, whole house vacuum, washer, dryer, freezer, or other appliances??