Why do Mars and Europa have precedence over Titan when it comes to future space missions?

Am I correct that because Mars is much closer, it will come first as far as manned interplanetary missions go? Russia is already designing a spaceship that will take Cosmonauts to Mars. Perhaps instead of a 'race to mars' with Russian & China, NASA should start planning a manned mission to Titan. I truly believe Titan has SO much more to offer than Europa, and even Mars because it is the only terrestrial planet besides Earth that has weather.