If you travel in coach frequently, getting upgrades on long-haul flights (especially redeyes) is really a significant quality-of-life improvement. Among other f

If you travel in coach frequently, getting upgrades on long-haul flights (especially redeyes) is really a significant quality-of-life improvement. Among other factors, upgrades are doled out by airlines based on the relative status tiers that passengers are classified in. And those classifications are relatively coarse (for United, there's a tier every 25k miles flown [1]), so if you're just a few miles short of the next tier, you find yourself doing the calculus on whether it's worth it to do a quick flight somewhere before the cutoff to get to the next tier. There are other benefits, too. Ones that matter to me: priority boarding is great on busy routes, because it means there will definitely be room for your carry-on luggage. And on United, higher tiers get automatic access to a few more inches of legroom in economy, which is great if you're tall. And you get lounge access on international flights, which mostly means that I can take a shower upon arrival when I fly overnight to Europe. [1] Airlines are now adding a dollar component to it, as discussed elsewhere in this thread, which roughly works out to "the cost of 25k miles' worth of regular-ish fare tickets"