Hi J.!
I have two sons, 15 and 11, and here are a few books and tricks that might help.
For books, try "Parenting with Love and Logic" and the author John Rosemond. Both are very different, very no-nonsense approaches. I use the "parenting" technique not only at home but in my (high school) classroom with great success. As for Mr. Rosemond, he adovcates a very 1950s style of parenting that, I feel, is refreshingly free of the guilt trips modern parenting puts on today's parents. My husband and I have his 10 tips for raising a healthy child on the fridge and read it constantly.
As for tricks of the boy parenting trade, I've found that the number one trick is to say what you mean and mean what you say. If you're not sure of the best course, simply say you need to think about it. If pressed for an answer, the answer is no.
Chores are a good thing. Give your grandsons age-appropriate chores, show them how to do them and make them do it. No fun stuff 'til chores are done. If someone misbehaves, extra chores. In my family, we always say chores are the price you pay for being part of a loving family.
Lots of unstructured play time is great. Let your boys play outside for at least an hour a day and let their imaginations take over. My sons have played explorer, bug scientist, carpenter, Star Wars, pirates, you name it, with anything they find in our (incompletely landscaped) backyard. At one point, they discovered shovels and my backyard resembled France duirng WWI...holes everywhere!
Severely limit all electronic gadgetry and tv. No, they don't need cell phones, game boys, hand held games, Wii, playstation, Nickelodeon, etc., etc. I firmly believe that the more time my sons spend focusing on electronics, the stupider they act. Instead, have your boys (re)discover reading, board games, crayons, cooking, the outdoors. Limited time as a reward is fine; everyday for hours on end is not.
Last but not least, boys need TONS of sleep. My 11 year old still sleeps nearly 10 hours a day. Recent studies show that sleep deprivation or lack of sleep symptoms are the same as ADHD in kids. The less sleep they have, the more hyper and unfocused they become. Good nutrition helps, too.
Ok, I've got to run to school! Good luck!