The original poster mentioned "propagation", as in propagation in general, not necessarily DX propagation. He said "tells you what bands are open."
For just propagation, WWV can work just fine. If WWV or WWVH aren't appearing, chances are less that you're going to hear that rare station from Southern Africa or Asia, although that could be possible. I suppose if you have an SDR waterfall, that will tell you more about general propagation than any website on the net. What the guy 20 miles away from you with the 5 element Yagi hears and what you're going to hear with your dipole may be two different things.
As for pursuing DXCC, if you don't actually hear them, you're probably not going to work them, at least with CW and SSB.
I am not a ham, so I don't have that particular issue (having to work them). However, in SWL if you don't hear them, you can't log them -- with SWL, hearing them is the only point.