Booking HA for first time and was going to use Main Cabin versus the Main Cabin Basic so we could choose a seat. However the flight while booked through HA takes HA to Seattle and then Alaska Air from Seattle to my home airport. It says that I can't do seat selection for the Alaska segment. Will I be able to go onto the AA site once my flight is booked and choose a seat and will there be an uncharge for that ? It's my first time flying either airline so not familiar with their guidelines and can't really tell off the website.