Guide
Is business class worth it?
Sometimes absolutely, sometimes absolutely not. It comes down to three things - and "because you deserve it" isn't one of them.
1. How long is the flight?
This is most of the answer. Under about three hours, business class is a ground purchase - lounge, luggage, queue-skipping, a better breakfast - because nobody needs to sleep on a hop to Paris. Between four and seven hours it's a judgment call about your own comfort. Past eight, overnight, the question changes completely: it's not "is the seat nicer", it's "do you want to arrive as a functioning human". A flat bed on a 12-hour flight isn't luxury, it's the difference between a trip and a recovery week.
2. What is the seat, actually?
"Business class" is a marketing name, not a product. On the same airline it can mean a private suite with a door and a proper bed - or an older seat where you climb over a stranger's legs at 3am. The same cabin name on British Airways covers both, depending on which aircraft shows up. This is the part almost nobody checks and almost everybody should: the seat matters more than the cabin name.
Aster keeps a seat-intelligence library of real aircraft layouts across 25 carriers, so when it compares cabins it can tell you which product you'd actually get - see which BA planes have the new Club Suite for a worked example.
3. What's the fare gap on your dates?
Business at 4x economy is usually a bad buy. Business at 1.5x on a night flight is often the best money in travel. The gap moves daily and per route, which is why any guide - including this one - can only teach you the shape of the decision, not make it. The answer lives in live fares.
The shortcut
Tell Aster your route and dates. It pulls live fares in economy, premium economy, business and first, shows them side by side with what the seat on your flight is actually like, and tells you straight whether the upgrade earns its money on this trip. That's the whole point of it.