Assuming Hilton will actually rent you a room at the correct government rate (my biggest challenge) the points are no problem. When requesting the gov't rate I am frequently quoted a figure well above the established federal per diem.

Most recent fun with this issue--being told by the folks on the reservations line that I could have a smoking room at the gov't rate but not a non-smoking one. Plenty of non-smoking rooms were available, but only at the rack rate. Ended up making a reservation for a gov't rate smoking room and then calling HHonors customer service office to get it changed. Although this worked, it took being transferred twice followed by 15 minutes on hold while they called the hotel directly to negotiate on my behalf.