Can't think of many places where HSR connects at airports (not only is it competition for airlines, it sort of defeats the purpose of riding HSR -- being that you could go from city-center to city-center). Not sure what the HSR plan is for Houston (or if there's space/a plan for it in downtown). Really think the Astrodome should be converted into some sort of rail hub, either for METRO or regional trains if it were at all possible. It would potentially provide [transportation] access, entertainment, and shopping options directly next to Reliant events. Can't think of any other possible use for the Astrodome.
How about a parking lot? Seriously, it's been 15 years almost. If we couldn't come up with anything by now, it's time to let it go. While its history as the first dome is significant, we're not talking about the pyramids and sphinx in Giza.
New Orleans is pretty much the only "walkable" city that consistently hosts the Super Bowl. Not even The Meadowlands has any significant business/attractions nearby. Seriously, I can't think of another city where the stadium is within walking proximity to main attractions. Not Dallas. Not Miami. Not Arizona. Not Tampa. Doubtful for Santa Clara. Maybe Atlanta. Maybe Los Angeles (only if they build next to Staples). So yeah, maybe New Orleans should just be designated the Super Bowl capital.
Politicians, and one neighborhood. In 2003 voters passed a referndum for 50+ miles of light rail but Afton Oaks, Tom Delay, John Culberson were able to stall it for so long that now only three lines will get built. The other two had a chance but voters voted against stopping 25% GMP payments in november because of a tricky ballot.
Big Oil has fought light rail in Houston. The politicians are in their pockets. They do not want to have Alternative Mass transit in the "Energy Capital of the World" unless it uses OIL or Natural Gas.