I've got the same problem almost. I'm in a PPR as well, and I've got Mendenhall, LT and Lynch...and can't decide between them. Right now I'm going with Mendenhall and Lynch. I hate sitting LT now that he's FINALLY available at what is supposedly 100% health. ESPN has LT projected at 2 points, and yahoo has him somewhere around 9 or 10. Is the Denver defense really that good? They limited NE to 17 but the rest of the offenses aren't anything to write home about, at least this year (Cin, Dal, Oak, Cle).
San Diego does have injuries on the offensive line, and LT maybe isn't 100% just yet, so there are some concerns there I suppose. But I could see LT putting up some useful numbers...and certainly more than 2 or 3 that I've seen projected in a couple of places.
That said, for YOU, I'd start Slaton for sure and then watch the injury report on Mendenhall. If Mendenhall gets the start, go with him, if he doesn't go with LT. Bush is a total bust IMO and is never a reliable start. I'll be starting Lynch for sure, and then if Mendenhall goes, he'll start...if not, I'll be taking my chances with LT.
I would wait until the last minute to set your lineup to see the status of W. Paker. If Parker looks good in warmups and is active, I would start Slaton and LT. If Parker has a set back or they said that he will have limited carries, I would start Slaton and Mendenhall.