+1 for dark chocolate, the darker (higher cocoa content) the better.
I don't consume dairy and I only like really dark chocolate. I find that it holds up in a tropical environment and it's very versitile. I'm just careful to put it in a separate ziploc and arrange it so it doesn't get crushed or smushed in my pack. I also like the heavier bars (ie > 3.5 oz) rather than thinner, lighter ones. And of course, I go for variety, ie. chilis, cherries, coffee beans, etc. so it won't be so rich. You can also melt it in hot water for yummy hot chocolate. Mint works good for this and it takes a litter rum or disaronno (almond liqueor) with it just fine as well.
You know what they say, once you go dark, you won't go back:)