I've never been statused with any airline so I'm not sure how much value to place on it (silver). How often can a silver expect to get upgraded to either economy plus or business? I know it is based on availability and silvers are last but is it a 5% chance or a 50% chance? Most important to me is getting upgraded on long haul flights to Europe and Asia. Do those have higher or lower likelihood of having business seats open to silvers?

I asks because I fly about 30k miles a year. Typically, like most people, I'm booking the cheapest tickets regardless of airlines. If I try a little harder to focus on United, I could get statused through them at an additional cost. I'm trying to figure out how worth it that would be.

Thanks