Have you ever noticed how often the melodic interval of the fifth is used in contemporary pop music?
It is a lot of fun to play with melodic fifths, which is what I happen to be doing at the moment in my new work in progress. For some reason having that interval of an ascending fifth running through my brain all the time makes me feel kind of perky inside. It is also the interval of unlimited possibilities. Think of all the "stuff" you can fit inside a fifth, particularly when you have different timbres to work with.