Government internship advice: application choices

[warumnicht]

I'm a 2L and am currently exploring my academic year internship options for the next three semesters. I won't mention the specific ones I'm looking at, but they can be roughly subdivided into two groups:

Group A: Bigger governmental agencies, work experience will probably open more doors for post-graduation employment, PAID.

Group B: Smaller, very specialized agencies that I would LOVE to work for, but the post-graduation prospects aren't great (because the field is so specialized and there are so few positions), and they are unpaid.

My dilemma is that I want to apply for both Group A and Group B internships right now (to maximize my chances of getting something), but if I take one internship over another after interviewing at both, will that preclude me from applying again for my 3L year? As in, will they recognize my application and not interview me again because I turned them down the first time? I'm particularly concerned about the Group B internships, since they don't get a whole lot of applicants and might hold a grudge.

If that's a real risk and I have to limit my options right now, would you recommend applying to Group A or Group B first? Group A will definitely provide me with more peace of mind because it's the safer choice. On the other hand, if I work for Group B now instead of as a 2nd semester 3L, that might open up more doors to what I would basically consider a dream career in that field.

Thoughts?