I'd say take the Polk off your list as it's not the same price range. It's currently 250 each, but there is no difference between the 75T and the Monitor 70 series II, or at least not a 100 dollar difference from the review I read hear on this site. If you aren't getting 150-170 on those each it really isn't a worthwhile deal. No reason to overpay for the Polk Monitor 75T. If you actually like Polk over the other two though then I'd say wait for it to drop to 300 a pair, or get the Monitor Series 2 for 300 a pair as there really isn't a difference between the two when you listen.
I don't really see regular deals like that for the Klipsch or the Martin Logan. I dunno which is better either and if you do a search I don't think you'll find a definitive winner among the pack. So if you can listen to both, do it, if you can't, I'd just pick the one with the better aesthetics. The Klipsch do have more of a low end though from what you'll read but you have a sub so that isn't really a big concern.