My recommendation would be working at Google, or possibly one of the startups. Finding a job that fits your temperament is great for satisfaction- many doctors make the mistake of going into the field they find academically fascinating rather than the one that has a practice they'll enjoy. (That is, they don't look at what hours a job will require, whether they'll have to be on call, how many patients they'll have / how much time each patient will take, etc.)

If you go to graduate school / do research, it will mostly be thinking about problems for extended periods of time. Ability to code is not very relevant, though it's important in industry. You shouldn't worry about being third rate- the intellectual bar for PhDs is around 5th rate (though you need other strengths to make up for that).