Here's a cool idea I picked up from John McGann at this year's AMGuSS. When improvising over a dominant 7th chord, play a major triad a whole step above the root of the chord. This enables you to hit all the natural tensions of the chord, without having to think of extension numbers (#4, b9, etc). This really freed me up when taking a break- rather than thinking scales, modes, guide tones, numbers, etc, I could go with melodies in my head and just think D major triad when I hit C7 if I wanted to get a little more out there. Hope this helps. Thanks, John, and feel free to chime in for clarification.
I laid the tracks, never rode the train.