Yep...Long flight and you know you have to go back home...
Actually, I flew to Singapore and back a few weeks ago, and so long as you're upstairs on the A380, coach is pretty comfortable. The food is great, there's reasonable legroom, even for a big ang moh like me, and there's tons of storage space. Yeah, I got pretty envious walking through first becasue it does look comfortable, but it doesn't look worth the extra $10,500. (my coach ticket would have been $1500 return, but I flew on miles)
This is really a per-use calculation. One way or another, you're flying to Singapore.
First class is $12,000. Economy is $1,400. The real question is, who's paying for the difference.
You're so rich it's not a factor? Enjoy.
You're on business? Is it worth it to your clients?
You're on vacation? See #1, are you so rich it doesn't matter?