Alaska Airlines partners with many of the airlines both in oneworld (like American, Cathay Pacific, Qantas, LAN) and Skyteam (like Delta, Air France, Korean) and also non-alliance airlines like Emirates. You cannot book first class awards on either Air France or Korean (business is the highest cabin offered).
I really like Alaska Airlines miles because they offer one-way awards on nearly all of their partners and most booking functionality is available on their website. One way awards allow an enroute stopover. So booking roundtrip allows two stopovers in addition to your destination.