That's an interesting set of choices. It's possible you get burned, but I can't see how you can get away from starting Harvin against the Lions. Matchup just too tasty to pass up. I'd flip a coin between Jones and D Thomas for the other spot. Jones gets the goal line work, even if they have no idea how they're splitting carries from week to week. I have a hunch the Niners are going to see more of Jamaal Charles than they'd like to, but it's just a hunch. D Thomas is up against a pretty good pass defense in Indy, but volume of throws from the Broncos today might make up for it. I don't like LT against a decent Miami defense, and Nicks is going to have his hands full with Finnegan, though I still am not as big a believer in the Titans secondary as some here.
Harvin and Thomas would be my starters. Good luck!