>Even men, who were too busy to spend much time with their own kids, are enjoying...

Sarah, you've used commas to set off a restrictive modifier. The sentence as written appears to describe all men, rather than the subset who were too busy to spend much time with their kids.

http://www.wisc.edu/writetest/Handbook/Commas.html#definitions

My dad was very involved with his kids and remains very involved with his grandchildren. He watches my children and never hesitates to help out with his other grandchildren. My sons have benefitted enormously from having a close relationship with their "Pop-Pop," who's like a second father to them. And he's benefitted from being around them.

However, sometimes a grandfather's involvement in his grandchildren's lives can re-open old wounds. The father of a woman I know was always too busy with his career to spend time with his children. Now, though, he wants to be there for his grandchildren. My sense is that he regrets missing out on his kids' childhood and wants to make up for it by spending time with his grandchildren. They are glad to have their grandpa around, but his daughter is angry that he didn't do the same thing for her. The hurt that she felt about his absence has returned now that she sees him with her own kids.

I have to tell you that a great father can continue to pass on his love and guidance even further. My wonderful father loved his own two girls and then did the same with his grandchildren and his great grandchildren We all had the benefit of his wisdom, generousity and day to day care in our lives. And he was truly a member of the greatest generation. He fought in WWII as a Ranger and was decorated with a Purple Heart and a Bronze Star. Then he became a firefighter and retired as a Firechief from one of the largest government installations in the United States. He then spent 20 yers in Civil Engineering as his final career. All this time he cared for us hands on whenever he had the chance. He could change a diaper and well as he could read blueprints.

Our family lost the great man this April as his great big heart just finally wore out and quit beating at 83. He lives on forever in each of us.

The downside of "active" grandparents occurs when they don't understand the fundamental difference between parenting and grandparenting. Parents are decision makers and authority holders; grandparents (by default) are not. I know of several families (including in my own) where a grandparent has failed to respect the parents' ultimate authority, which can cause a very hurtful rift. In cases like these, it would have been better for the grandparent to be less involved.

Even men who were too busy to spend much time with their own kids are enjoying the chance to be involved with their grandkids.

Men who do this are usually resented by their grandkid's parent. They deserve it. If you couldn't be bothered to spend time with you kids, trying to re-live that with a grandchild doesn't make up for that.