Bill Kanasky, Jr., Ph.D. talks about how to select experts for trial testimony. One option is to pick national experts and another approach is to choose an expert who is more local to the venue. Bill walks through some important considerations when selecting an expert witness: 

The decision about who would make the best choice as your expert depends on a number of factors:

Oftentimes jurors prefer local/regional experts, however, they have to be a good witness and their testifying performance is as important as their expertise and local presence. The combination of all these considerations (local/national; percentage of income that comes from testifying; volume of work done for one side vs. the other; etc.) is what matters to jurors. Lastly, remember that juries don't make decisions on liability or damages based solely on expert testimony.