31,000 to 35,000/year isn't a high paying job, and that's for the majority of GS jobs. As far as the benefits? Yes, they get pretty good sick leave, and there is vacation time they can get (but it's equivalent to what many companies allow, only a couple of weeks per year, which is what most major companies allow, their vacation time is about half of what the military gets). And no, they don't get free medical like the military does. In talking with many of the government workers that I worked alongside, the only thing they really saw as an advantage was their job security. If a person has been in government service for a fair amount of time (several years), it takes damn near an act of Congress to get them fired.
I remember one example at a command I was at once. Seems that the Education Officer (a GS-6), who was responsible for administering the Navy Wide Advancement Exams, as well as providing and grading all courses that enlisted personnel used for rate advancement somehow "forgot" (they had personal problems that I won't go into here) to mail in the exams for that cycle. Not only did it cause a big mess for the people that took the exam, but it also had an impact on the exams given throughout the whole Navy. Dude went through several investigations and was eventually removed from his EO job, but for some reason that I can't fathom, was allowed to continue in government service at a different job. If that had been a military person who had done something like that, it would have resulted in NJP with a bust and probably a less than honorable discharge at best, courts martial at worst.