I'm going to go ahead and highly recommend the OP go to the LBS and test ride a few bikes. Then come back and get more advice. Ride both 26" and 29". At your size and road bike background, you may well prefer a 29" XC bike, but it's always best to test ride as many different styles as possible to see which you prefer. And I think c_mack9 makes a good point about getting last years model if a LBS has one available. It's a great way to get more bike for your money in MTBing. The bikes don't generally change that much year to year to make much difference, if any at all.