I tried running a 24/36 on my 29er to get a good mid-range spread back in 2005. Ran into some serious issues with chainring/chainstay clearance- the hardtail frame was not designed for anything bigger than a 22 on the inside. Due to flex, the chainring actually gouged out a channel in the chainstay, putting a nasty crack in the frame (unflexed, I had 1-2mm of clearance for the chainring). Full suspension frames with a chainstay yoke may not have as significant a problem there, but look out with a hardtail frame.
I also found that a 36 meant that I had to shift down to the 24 a lot more for climbing. With a 32, I can pretty much keep it in the 32 all the time, even on significant climbs. I much prefer giving up a couple top-end gears to keep from having to downshift so often.