I am picking my daughter up from Alaska Air. Can I greet her at the gate? Or where am I able to wait at Sea Tac Airport

Yes, you can. Nothing has been changed there just make sure you cover your face with a mask. You can meet with her as usual at the baggage area.

Check the section about unaccompanied minors on the Alaska Airlines website.

You can't meet her at the gate unless she is an unaccompanied minor. If she is then go to the Alaska desk and the will get you a pass for security. Otherwise, you can park on the garage and wait for her where her arrival terminal exits the secure area, wait for her at baggage claim but you need to know a little bit about what you are doing in order to find the correct carousel.

You also can wait in the standby parking area (it is free) next to cargo road, works great if both of you have cell phones

You have to park your car on the floor