I think it would be hard to make the decision based on your credit score, b/c there are always different answers about what affects, and how much. If you don't make big mistakes, like defaulting, I'm sure your credit score will take care of itself.

If you feel like you want more flexibility in your limits, then call and see what you can get. I have around 6 cards, at least 2 have limits over 10k, and my credit score has been over 800 for years. I've opened and closed various cards, and had limits rise over the years and haven't been constrained in getting mortgage or refinancing. 

What should my credit limit be?

  Some psychologists believe that 'while object permanence alone may not
  predict communicative achievement, object permanence along with several other sensorimotor milestones, plays a critical role in,
  and interacts with, the communicative development of children with
  severe disabilities'. This was observed in 2006, in a study
  recognizing where the full mastery of object permanence is one of the
  milestones that ties into a child's ability to engage in mental
  representation.


Source: http://en.wikipedia.org/wiki/Object_permanence#Recent_studies

Thank you very much.
