Watch the The I-ii-I-IV Ascending Bass online guitar lesson by Ravi from Guitar Lab: 30 Rock & Pop Progressions
Our ears love to hear step-wise moving bass lines, so we can take a I-IV chord progression and repeat it twice, but using some substitutions in order to create the ascending bass line. This is essentially capturing the sound of a I-IV-I-IV, but by employing the relative minor of the IV the first time (the ii), it creates more depth and movement. By ascending the bass notes stepwise, it gives a nice flow and an added sense of evolution or "lift." This is best in the open position chords since the third chord in the progression is a bit difficult to employ in a barre chord. In the key of G, this is a very guitar centric progression because of the voicings of the open chords. Add some strumming variations and so many songs will creep out of this ear-catching ascending progression.
Examples: Uptown Girl, Heart of the Matter, I'm Gonna Wash That Man Right Out of My Hair, Blackbird