I really like TAM. Flew 2 14h flights with them. The planes are new and comfortable and the food is amazingly good. The downside can be a long wait in Sao Paulo. That airport is absolutely shitty. Only good thing is a per hour hotel in the hallway between terminal A&B.
I had a very bad flight with Alitalia. Absolutely no attendance during the night, quarrels between the flight attendants (they are there for your safety for godsake) and the food is, strangely enough, very bad.
I can also advise a light sleeping pill (f.i. Somit). This ensure at least some hours of sleep which improves the experience a lot (as in not being ther, haha)