Today, NASA announced its plan to develop a heavy lift vehicle (aka rocket) called - rather uncreatively - the Space Launch System (SLS). It would use many parts and technologies from the Space Shuttle program in an effort to save money. But despite that, the cost is huge: $3 billion annually through the first test flight in 2017, for a total of $18B. That's too much, as far as I am concerned, especially in light of the fact there is no defined need for it. There's plenty of hoped-for missions amongst human spaceflight supporters, such as to the Moon and to Mars, but those are entirely unfunded at this point. If the cost was lower, then I would support the program despite its speculative nature. But at $3B per year, the funding will definitely eat into other programs. I have no idea if the $18B price tag is justified in terms of the manpower and materials needed to accomplish the task, or if that number is bloated due to too much contracting and sub-contracting. I do know that making the SLS man-rated will add to the cost, and as I explained before, there's no reason to do so given the parallel development of commercial capsules and the availability of the Russian Soyuz vehicle (though the Soyuz launch system had a small problem last month).
At this point the best option for a heavy lift vehicle is the Falcon Heavy, which has a test launch scheduled in early 2013. It will only have a maximum capacity of 50,000 kg to low-earth orbit, as compared to 70,000 kg for the first launch of the SLS, which is intended to have a maximum capacity of 130,000 kg. But the Falcon Heavy will be available much sooner, at a much lower cost, and, again, as of now there is no defined need to lob something that heavy into orbit. If for some reason a larger spacecraft is needed, it can be assembled in orbit, just like the Space Station has been. That would add costs to a mission, but probably not so much that the $18B SLS program would become justified.