Watch the Jagged Blues 9 online guitar lesson by Carl Verheyen from S.W.A.T. Blues
Intervals for the sake of intervals are not what I try to accomplish, but when they are used to spice up a scale or create a melodic arc they become a valuable tool. Slides and bends are a matter of style and should be used to complement the improvised melody you're composing on the spot. I try to practice these elements as a part of the lines I come up with. The mental exercise I describe in this lesson is very important for opening up your range. I can't stress this enough!