Damnation is by far one of THE best albums to get stoned to. Some of the fans that are more fond of their heavy shit talk crap about this album a bit, but it's truly a wonderful piece of art with great musicianship, but in my opinion it's their best work to date.
Yeah, Damnation is pretty tight. I like Ghost Reveries a lot, I think it's a pretty decent blend of their heavier stuff with the more chilled-out stuff on Damnation.
Opeth is essentially the meaning of EPIC WIN. I personally love The Ghost Reveries, although Blackwater Park is really haunting and beautiful too. All in all, a very talented and just really, really amazing band.