I think that depends on the agency. Where I work, we do actually change our travel plans fairly often (usually due to equipment issues, but sometimes due to changes in rules regarding where we can go and what kind of meetings/conferences we can attend, or issues associated with sequester or the budget). This is enabled by the fact that our government air tickets are fully refundable/changeable, so there isn't a big hit in changing the trip dates when a problem arises. Of course the extension of that approach is that we have an unofficial rule to only book cancellable hotel rates, as we'd be personally responsible if we booked a nonrefundable hotel stay and then had the associated trip cancelled for any reason. Were Hilton to make such a change to their government rates, it would be the end of HH for me, as I wouldn't take the risk. I have a number of colleagues who have trips planned for next week, which all may be cancelled if the Government shuts down yet again. It seems very unlikely to me that Hilton would make such a change, as they'd lose quite a bit of business.