Regarding Merino Wool. I've been using Australian Merino Wool shirts, layers and sweaters daily for my commute and they're awesome. I can get away without washing it for 2-3 weeks and it never smells. But that's 45 minutes one way, easy riding.

On my first overnight trip last weekend I wore the Merino shirt. It was in the 70s, dry and breezy. After all day it was so soaked in sweat that large spots of salt started forming. They dried into disgusting, sticky stains. It still didn't smell but I was weird to the touch, I couldn't wear it. And despite the dry, breezy weather the shirt remained wet on me most of the time. It definitely takes longer to dry than synthetic. I don't even want to think how it'd look like in typical NY Summer weather: 90F/90%.

So for touring I'm back to synthetic shirts, the loose type, not jerseys (I don't like them too close to the skin on long rides). I can change them even during the day, wash them in any bathroom and they'll dry in no time. They also remain dry on you most of the time.

Wash your armpits whenever you can and you should be OK, that's the major source of the smell. Also, shaving your armpits (cutting short actually to avoid skin irritation that's caused by close shaving) will help with the smell too and make them easier wash or wipe with WetOnes.