Curious about traveling

Hi, I'm still a student, but I'm curious about travel nursing. I have a 2year obligation with a hospital when I get out, but once that's done, I'll be open to anything. I just wanted to know what areas(specialties) are the most requested/ highest paid travelers, and what cities/states generally pay higher as well. I'm really interested in Mother/Baby, L&D, PP etc. DO most agencies require that you have a med/surg background for those areas, or is straight OB experience ok?