I think it depends on the quilt...some need a border, some don't. Some need more than just plain strips. Some have borders simply to make the quilt bigger...some don't because the quilt is big enough. I have nixed a border on a quilt because the quilt was big enough, even when I thought it "needed" a border, but I really didn't want it bigger. Sometimes I do two borders...sometimes one...sometimes more, or none. Depends on the quilt and the situation.
For the first time, I'm trying to incorporate something "extra" into borders for a quilt. I *need* to put borders on it to get the size I want, but I want to do something more with it. I may do a scrappy border...or maybe one with a few star blocks as corner stones (it's a little boy's alien quilt). I don't know yet...this one is a design as you go...lol