How to buy different fare classes?
 

So, I've been trying to figure this out for awhile now. I am traveling SFO-NRT-SFO in a few weeks and I still have 1 GPU to burn this year. The round trip on W (or higher) is about $1,800, but it would be much cheaper if I could do one way in a lower fare class: since I only have 1 GPU, I really only need 1 of the legs (inbound or outbound) to be on W.

I cannot for the life of me figure out how to do this on the UA website. If I go advanced search and select W or higher fares I get the price for the entire itinerary. If I buy two one way tickets everything is more expensive. So, is there a direct way to do this (or maybe another website)?

As you are a 1K and don't get charged for calling, why don't you call reservations? They should be able to do it for you.

I agree with Baze, calling is the easiest way to get the specific fare class needed per segment, etc...