I travel quite a bt for work, and this last time I got upgraded to first class for being such a loyal customer to one of the worst airlines in the nation (my work doesn't let me make my own travel arrangements surprise surprise).
The difference between coach and first class was like night and day. The whole flight crew was falling all over themselves to try and make my 3 and a half hour flight the bestest aviation experience ever. I had a waitress that would bring me practically anything I wanted.
Bring me the head of a pig!" "Have someone from coach fiddle for me. Amuse me!"
It was a little bit silly. They gave me free snacks, drinks (alcoholic or non), a full meal, hot towels (which if you have no idea why your stewardess is handing you a hot towel is quite an awkward experience), pillows and blankets, headphones and well wishes at the end of the trip.
By the end of my trip it was actually making me a little uncomfortable. Every time I made eye contact with the uber-perky flight attendant, she would come over. "Do you need anything?" for the upteenth time. Smile, "no, I'm fine," for the upteenth time.
I would never pay for a seat in first class, partly because the extra $1000 is not going to get you there any faster, and mostly because when I woke up halfway between Phoenix and Chicago, my big comfy plush first class recliner still gave me a crick in my neck!