The benefits of traveling to Mars with a manned mission versus an unmanned mission would be countless. A droid cannot have the intelligence of man to see all that there is to find on the surface and below. There are so many things we as a planet could change our world for the better, perhaps new medical advances could be found, there could even be a new species found on this planet.
Economical? Unless it's helping eliminate homelessness and poverty, nothing about the space program is even remotely economical. The Earth is heading toward an environmental catastrophe but it's so many years down the line - centuries, I should say - that the only sort of funding the government should be providing is for the people. People are still unemployed, still starving, still living in shattered communities. And you want to send somebody to Mars? What good is that going to do?
Mars is the closest thing we have in the solar system to another Earth. With the possibilities of past life, water, or teraforming, a manned mission to Mars seems like a very exciting prospect!! However, there are many challenges that we have to overcome and understand before we even think about putting up the probably $1 Trillion to foot the bill for something that may cost people their lives in a 3 year journey to Mars and back. When they figure out how they're going to combat atrophy of the muscles from a low-gravity environment, we can revisit this topic. Until then, maybe we should try to capitalize on the moon first.