I love ruler work! Although I admit it's a slower process and you have to practice (and some rulers are just easier than others!) Several of the national level quilters have their own ruler lines--check out Dusty Farrell, Deloa Jones, Jamie Wallen, Linda Taylor, Kim Brunner--all have websites and all have youtube tutorials on-line. Like Feline Fanatic says, you do still need to mark registration marks to get the precision you are striving for. I don't like using channel locks for my straight lines simple because they do not adjust for the quilt that may need a little nudging! Kim Brunner has a great video on the HandiQuilter or APQS website on getting the quilt squared and ready for ruler work.
One tip from an owner of too many rulers!: pick ones that fit your hands! too long rulers tend to slip more and no amount of "stick-um" really solves the problems!