No such site exists...loads are proprietary business info, most airlines don't want to release that to just anyone. Normally only employees can get actual loads, although the SWA non-rev phone number will give non-employees a rough estimate.

Yeah, you can also get a "good, so-so, not good" if you're nice when you check in.

travelocity.com has available seat diagrams for SOME flights. I usually check it before I bother listing for non-rev. So far it's worked out well, though time consuming.

What I do is look at the schedule, then go the airlines web site and look at seats available, or view seats, or whatever that airline designates it. (NWA,CAL). Seems OK.