Aviation Week's latest issue provides an in-depth look at Boeing's new heavy lifter, the Delta IV "Heavy", the largest all-liquid fueled rocket launched since the last Saturn V took off more than thirty years ago.
Boeing is pitching it and a slightly smaller Delta IV Medium as primary launchers for NASA's new manned space exploration efforts. While not man-rated as yet, with its liquid-fueled design and new engineering Boeing is calling it "man-compatible", claiming the full rating should be relatively straightforward. They also point out that NASA could save a great deal of money on ground support because the Delta IV launch complex is already in place and fully functional.
Of course, such a completely reasonable proposal will probably have zero chance with the "new new NEW NEW NEW!!!" attitudes NASA historically holds dear. The Astronaut Office in particular has already gone on record as stating "human rating should be designed in, not appended on." However, their problems seem to mostly center around the difficulty of "safing" the solid booster systems found on the smaller "medium" Delta and competing Atlas designs, which the all-liquid Heavy does not have.