For some reason, I perceive a bias towards going to Mars at all costs in your poll. Perhaps it is the way that the options are stated, where one seems extremely positive, implying swift action, and the other specifically states that "doing nothing" would be the end result. A great many people believe that money will have to be made in space if we are to continue our activities there. The most likely endeavor which will be profitable will be processing materials in a zero-gravity environment, especially those processes which require large amounts of energy. In order to be able to do these kinds of things, we will need to know how to keep people alive in space for long periods of time, how to construct habitat and processing facilities in space, and how to keep these facilities operational over extended periods of time. These are the primary reasons for having the International Space Station, and they could be performed in orbit around the Sun, around the Moon, or around Mars. However, our technology for accessing space limits us currently to low Earth orbit.
I disagree with a number of things which Mr. Zubrin says, starting with his comparison of NASA budgets during the Apollo era and today. During the Apollo era, NASA was focused almost exclusively on manned space exploration. Currently the agency is involved with a wide array of programs which have nothing to do at all with space exploration, manned or unmanned. So to say that the entire budget of 18 billion dollars is going into space exploration is incorrect. Space exploration accounts for a little less than half of the NASA budget at this time.
Mr. Zubrin states that Mars is "...currently within reach..." of manned exploration. He supports this statement by proposing a system for utilizing resources found on Mars to provide the life support and propellant needs of the majority of the mission. This system has never been proven under actual use, therefore it is erroneous to state that Mars is currently within reach. This is comparable to stating that it is safe to jump out of an airplane with a parachute which has never been tested, at all!
Mr. Zubrin states later in his testimony, "If we can go to Mars, and find fossils of past life on its surface, we will have good reason to believe that we are not alone in the universe." We already have good reason to believe that we are not alone in the universe, merely from the statistical chance that life would arise on only one planet among the trillions of stars that we can see. Basing our choice of destinations upon purely scientific goals also leaves our space program vulnerable to deep cuts, because science is never considered essential to our economic survival.
While I agree that that a definitive goal in space would have positive social implications, I seriously question the value of a destination which most people cannot find even when it is visible from Earth. A point of light in the sky is not a place in the minds of many people, or it is the same as a star, infinitely far away. The only celestial body which the average person could locate unaided is the Moon, and the Moon is also the only body which shows a visible disc. In terms of motivating young people to get involved with scientific careers, or to support space exploration, a goal which does not have to be explained, pointed out, and justified seems to me to be far more valuable.
Many people believe that colonization will the next step in space exploration. This view seems very unrealistic to me, because of the costs involved versus the potential rewards. Industrial development does not require colonization, especially in an age when robotics has become such an advanced field. People who work on the North Slope of Alaska don't usually end up living there full time, they rotate in and out. The same holds true for off-shore oil rigs, drill ships, and many other resource extraction sites.
I firmly believe that people will live on Mars someday. I also firmly believe that it will not happen until after we have begun extracting resources from the Moon, asteroids, and possibly Mercury, and have established industrial space stations processing those resources. The costs of space flight will come down drastically as we move our industrial base off planet, which will make colonization much more affordable. Considering that the government has absolutely no place establishing colonies, that will be a critical factor.
People who insist that we should make Mars our primary goal are quite possibly hindering our space exploration effort. When those who are not familiar with space exploration hear a multitude of goals proposed, they can become confused, uncertain of what is the best course of action. If space exploration becomes well established, financially rewarding, and safe, we will eventually get to Mars. If we make Mars our primary goal, we may threaten the long term viability of space exploration, as people perceive that they are being asked to pay for what should be a privately funded effort with little foreseeable monetary returns.