I fly business class whenever the trip is more than 5-6 hours. And since I'm in New Zealand at the bottom of the world - almost everywhere takes longer than that.
Business class is expensive, but is first class that much better... considering you're spending twice as much as business? (Which is 5 times more than coach?)
Here's a look at 9 of the most opulent first class airline seats to travel in comfort from Business Insider.