Mine usually only get water or milk. Dentist and pediatrician both recommend no juice. When we have juice (once every 2-3 months), I serve 1/4 juice mixed with 3/4 water.
For you, how about splitting the Capri Sun in half (part at lunch and the other half for dinner) and using water as the other half? That way, your kids won't get any more sugar and their taste for sugary drinks will lessen. Over time, you can probably even phase out the juice altogether.
FWIW, my DH is a soda drinker and my kids have never asked to try (they're 6 and 4).