I agree with GetSetJetSet - I am not overly tall (6'2") but I have had back surgery and 8 hours in Y would kill me. I've been to Bangkok twice and am going back in December. I'll have a 14 hour flight (2 hour layover) and then another 7 hour flight. If I spent all that time in coach I would need 3 days to recover. Having said all that Y tickets for my itinerary were a little less than 2K my C class tickets were 4K. Double the price but it's worth it to me.
I think this is personal issue. My wife and I were talking yesterday and some friends of ours, who are extremely well off, will never spend the money to fly C or F. On the other hand they've spent $ 125,000 on two new cars. We own an 06 Infiniti & a 98 Mazda.
They drive in style we fly in style!