This comment doesnt belong I think because it is a matter of personal taste
rather than a general truth.
Don't waste you're life trying to get a "huge sounding guitar tone like XYZ's album" with a solo'd guitar, you'll never reach it without a good bass tone underneath
But what if I like the guitar tone from XYZ's albums?
http://www.youtube.com/watch?v=GXKFmt-a-FU&feature=player_embedded
There is no ampsim out there, not even ReValver, that has the same mojo and feel then a good mic'ed amp. I've been playing guitar for over 10y now and I've seen the rise of amp sims and they don't sound the same yet.
Ampsims for pre-production: yes
Ampsims for final: hell no. Rent a good amp or send your di's to someone for re-amping
Don't mix on headphones.
Don't mix on headphones.
Take a break or get some sleep. Sometimes it sounds better the next day.