When I went to 37s I jumped the gears to 4.56...perfect combo in my opinion. Gave me my 'get up and go' back and didn't kill my highway top end. Plus seems to be really good off-road as well; granted the last couple of years the truck has seen mostly fire trails and dirt roads.
I did a couple days in Moab a few years back with the stock setup and I actually think 37s/4.56 would perform even better...I'll find out one of these days when I get around to it.
Here's the site and gears/kits I went with:
http://www.trailduty.com/index.php?c...cc7ddaf3e34c5f
...I had the dealer install them and haven't had a minute's problem since (been about 2 1/2 years I guess). I couldn't tell you what they charged as I had a lot of other suspension work done at the same time.