My $.02. My wife and I are 60 and our daughters are 28 and 31. They've turned out well. One is married but no grandkids yet. Kids are wonderful and a joy, and we had a lot of fun with their out-of-school activities like swim team, soccer, softball, and basketball. Coaching them in basketball was a blast, and then high school sports was really fun when the talent level and coaching was a bit better. I'm Catholic and I raised them Catholic and the Sunday school, first communion and confirmation process was very rewarding.
But raising kids it's not always easy. They can be a pain in the ass and, speaking bluntly, if a person is extremely selfish, he/she may be better off not having kids. They also are, or can be, extremely expensive depending on where you live, your peer group, summer camp, choice of schools/colleges, etc.
It's been mentioned before, but you really never can be prepared for kids. It's crisis management 24/7 and in our experience there was always drama. And you never know what you are going to get. I've seen the nicest parents end up with rotten kids. Shit happens. Shitty kids do not necessarily come from bad parents. In my experience, raising our kids in the Briargrove and Memorial areas of Houston, the kids that we know that did not do well were early drug and alcohol abusers. Sadly, some of them are already dead.
There's no guarantee it will work, but you'll have the best chance of ending up with good kids if you get to know their friends and make sure their friends are good kids. What a "good" kid is can be subjective and I won't engage in a debate on what it means, but if your kids are hanging with a bunch of druggies/hoodlums/criminals, that's not a good thing. Making sure your kids socialize from an early age with other kids that you deem acceptable can go a long way.