If you fly a lot on long hauls, you'll quickly succumb to economy class syndrome if you spend all your time there. Once or twice a year, it is now problem, but not being able to sleep very well for 11 hours straight gets old quickly, and there is only so much content to go there in their entertainment system (if you are a frequent flyer, you've seen all of it)...not to mention your butt and legs just start getting sore after awhile.
Even though I'm not really a frequent flyer, I generally buy business class when they are on sale. E.g. Beijing to Bali on Hong Kong Express for $900 roundtrip (vs. $500 for economy), or Beijing to LA on ANA for $2000 last minute one way (vs. $1500 for economy, and since I was moving, it was tax deductible at the time). You can find some good deals, especially in Asia, and the experience can be worth it.
Even though I'm not really a frequent flyer, I generally buy business class when they are on sale. E.g. Beijing to Bali on Hong Kong Express for $900 roundtrip (vs. $500 for economy), or Beijing to LA on ANA for $2000 last minute one way (vs. $1500 for economy, and since I was moving, it was tax deductible at the time). You can find some good deals, especially in Asia, and the experience can be worth it.