Best seats at the Tokyo Dome

I am going to try to score seats to see a Giants game at the Tokyo Dome (Giants vs Tigers or Giants vs Carp - both Saturday day games). If I'm not concerned about cost, which seats are the best for a tourist to aim for? As someone coming from a country without a Baseball culture, it is kind of confusing trying to decipher the setting chart, especially not knowing where fan club people generally buy out tickets first. Is it going to be impossible to get infield seats? I read the S seats are more expensive but there are not as many spirited fans there - are they easier to get? I will take anything bar the bench seats as I have some back issues, but what would be best to aim for?