The thing is, Sam, pants arent apt to be that comfortable in a northeastern summer. Its likely going to be hot, humid, and stickyhardly weather for pants that are heavy enough to keep out brambles and protect legs during scrambles.
Still, there are two routes you can go. One is a fairly light pant that affords you some leg protection and water-repellency but doesnt weigh you down. Patagonia's Continental Pant ($75) is made from a durable polyester/nylon blend thats light but tough. These pants have a water-repellent treatment so light rain will bead up and run off. And of course they offer excellent sun protection. A good all-around summer pant.
Another nice light pant is the ExOfficio Nio Amphi Pant ($70). A bit lighter than the Continentals, but they still offer decent abrasion protection, along with water-repellency and good breathability. Plus they have cargo pockets.
On the somewhat heavierand more expensiveend, take a look at Arc'teryxs Gamma LT pant ($169). These are a light soft shell pant, which means they are warmer than a pant such as the Continental. But theyre remarkably breathable, and super-comfortable when scrambling or engaging in other activities that require a lot of agility. Plus they are tough as nails. Nice pants.
Hope that helps. Have a great trip!