Good business class configurations allow you to lie completely flat.
Depending on the configuration you may have a real (narrow) bed feeling, or you may be lying in a sort of tube with not much space to move, but definitely completely flat.
If the price is not outrageous I always go for a business flight on long haul.
The price delta is usually in the thousands of dollars though. That said, especially for trans-Pacific I'll often try to get an upgrade using a combination of miles and dollars.
It amuses me that there are people think "nah I won't spend the extra $3k to make my trip livable" while working an industry where 30 year olds are paid $500k a year for writing a bit of javascript.
Why would the amount other people in my industry make have an impact on what I can afford? Much less whether I'd put up with a little discomfort for an extra $3k in my pocket.
Also funny how you yourself come up with the ridiculous salary of $500k, something ~nobody here will ever make, as the amount that finally makes $3k sound trivial to you. I agree with that much. That's the salary that would make me finally consider paying $3k for leg room.
Most people in tech are not making $500K to write Javascript or anything else. And, even if you make a fair bit of money, $3K isn't a trivial sum to make even 12-16 hours of air travel a bit more comfortable. (It still isn't exactly fun even up front.) I do sometimes use miles and a co-pay to upgrade when I can but, generally speaking, I can get a lot more bang out of that money on other things whether meals or other experiences.
That's limited to the US West Coast, almost exclusively.
You need to be level 7+ in a FAANG anywhere else in the world to make anything near that. And you definitely won't be there with "a bit of Javascript".
Depending on the configuration you may have a real (narrow) bed feeling, or you may be lying in a sort of tube with not much space to move, but definitely completely flat.
If the price is not outrageous I always go for a business flight on long haul.