It's also worth noting that having the seats blocked at booking or seat selection is no guarantee. My parents report that several rows in the back of the plane (MCI-SEA) recently had every seat filled. The Alaska agent announced in the gate area, "Because this is a very full flight, you may be seated next to someone you don't know. If you are not comfortable with this, we will try to rebook you on a different flight." Sigh. Thankfully, my parents were in Econ+ where the spacing was maintained.