There is a lot of thoughtful, well-reasoned commentary here. I will add my own two bits.
I am in my mid 30s and will be married within a year or two. I am also planning on a PCT thru-hike.
I read about a guy who worked very hard to pay ahead the mortgage….This could be done with careful spending and planning. This, of course, is tough to do with kids and their unexpected bills. But it isn't impossible.
But the money component is but one facet of the decision.
You have to ask yourself:
1) Can you stand to be away from your family for four plus months?
This is a huge consideration. Bill, who hiked the PCT in 2007 was in a similar situation as yourself. You can follow what happened on YouTube, including the unexpected ending
http://www.youtube.com/user/wgbatche
I don't have kids, but I can imagine that you can grow rather fond of them.
2) Do you have the support of your family?
I don't know if this can be stressed enough. I happen to have a girlfriend who is very supportive of my hiking goals. But every situation is different and everybody has their own perspective on this.
Your family needs to understand your desires to thru hike.
Getting your family involved is a great first step. While you are out having fun, they will be left at home. I really think it's important to make them feel connected to your hike, that they are absolutely critical to your success as a hiker.
How to do this? Make them your support crew.
Now depending on the age and interest of your kids, the next steps are suggestions that I've read worked for other people.
Make a huge wall map of the entire trail with the kids. Have them help you figure out where to stop for resupply. Make it their job to track your progress. You can get a variety of tools to do this, including the SPOT tracker, that will send them your GPS coordinates.
Dehydrate food together as a family. And then prepare the food using your camp stove and have everybody partake in dinner. Use your finest china to enjoy this succulent dish. It's an experiment that will surely have mixed results, but one that you can laugh at down the line. Have everyone decide on what you should take and what should be left behind.
Make up T-shirts with a logo that the kids come up with.
Show them videos from the trail you plan to hike (there are plenty of videos on the net and on DVD – heck, I will loan you mine! Just ask.) If the hike runs near where you live, take a short hike along the trail and camp overnight.
If your experience is anything like mine, nearly everyone will expect that you will be killed the minute your step into the woods. Your family may or may not feel the same, depending upon their experiences in the outdoors. That's why it's very important to make their experiences in the outdoors positive. That may mean tuning down the *we have to hike 20 miles and gain 4,000 feet today* hikes and settling for the car camping with plenty of snacks experiences. The important thing I suppose is to give them a good vibe about the outdoors and boost their confidence in your ability to survive without incident.
Remember, as your family will be left behind they are subject to the Uncle Al factor. Everyone they know will hear about your trip and then feel it necessary to tell them about the time Uncle Al was torn asunder by a pack of rabid Dingos and how if only Uncle Al had heeded the warnings of his family, this tragedy would have been averted….
Section hiking is a real solution. I met a guy and his daughter who were section hikers along the AT. He was in his 40s, she was 13. It was dad-and-daughter time for two weeks every year along the trail. I met them while hiking in Scotland and they spoke of their upcoming two-week stint with eager anticipation. It was something the two could share.
I met another guy who basically flew home for a week out of every month on trail to attend to business and family. Yes, this was expensive, but he said that he enjoyed the break and the chance to reconnect with the people important in his life. This could be easily modified.
I also met a guy along the trail who averaged about 20+ miles a day on the PCT and had lost 70 pounds in doing so (he was still pretty chubby when I met him.) He had a 1 and 3 year old at home with what must have been the most understanding wife in the history of the world. He was scheduled to finish the PCT just shy of four months. I asked him how he felt about being away from his kids. He said he cried on more than one occasion because he missed his family.
Here is a small discussion on marriage and thru-hiking that appeared on the PCT-L mailing list.
http://mailman.backcountry.net/pipermail/pct-l/2008-February/014350.html
http://mailman.backcountry.net/pipermail/pct-l/2008-February/014311.html
http://mailman.backcountry.net/pipermail/pct-l/2008-February/014468.html
As for your wife, well, she will need to be reassured and made to feel more important than any hike. I think it's important to be honest about how you would view the situation if the shoe was on the other foot. If she were to take off for four months tomorrow and leave you with the kid(s) and household responsibilities, how would you feel about that? Surely, you would be supportive of her desires but it is likely you would have bad days too where you feel like you are getting the short-end of the stick.
I think the important thing is to make her feel that she's your No. 1 consideration, even when your out on the trail. Write letters, schedule phone calls, make videos using your digital camera where you talk to her and send her the card in the mail. Plan to meet along the trail for a few days of R&R.
I hope some of these ideas help! Best of luck to you!
Dirk