Well, the only other DC cardholders I know are the ones here on FT, and they may not be representative of the whole membership. However, most of us here ceratinly either transfer to FF (airline) programs or to hotel programs. (I, in particular, have found it especially valuable for some hotel programs in which I have few opportunities to earn points other than from occasional stays or DC transfers, because they don't have shopping or dining programs like airlines do, and because I can't earn miles from stays in hotels to another hotel program the way I can to a choice of airline programs.)

A common use of DC transfers, I would think, is to top off when you don't have quite enough for an award (either in an airline program or at a hotel program). That (rather than staritng from 0 and transfering the full amount needed for an award) is I think how I've always used mine to date. I tend to leave as many points as I can for unanticipated top-off needs myself (rather than transferring out everything I have as soon as I have it).