Yeah it must be rough if you actually could be home every night to tuck your kids into bed or to say good-bye to them in the morning before you went work.
I love 12s. That is what I did on CCT and Flight as well as now in the hospital. I have not missed doing 24+ calls in 24 hours with the FD. Those who enjoy the 24 and 48 hour shifts the most probably don't have a family life.
If anything has ruined marriages in the FD/EMS it is the 24 hour shifts and jealousy. Those working don't have any control over what their spouses are doing at home "alone" and those at home want to know who their spouses are doing at work. From the threads on the EMS forums, it there little doubt how something like that could have crossed their mind.
What if you work an 0700-1900 or an 0800-2000? All you'll be able to do is say good morning to your kids or tuck them in to bed. When you work 24's you can actually take them to school in the morning, pick them up after school, take them to the park in the afternoon, or to practice if they're older. If you need to be off for a function, you can do an exchange for 5, 8, 12 hours or whatever. I'll take a few days a week where I can spend hours with the family rather than see them for a few moments when I come home at 2100 hours or so.
When I worked all nights for hosp based EMS, my wife's complaint was that I was never home in the evenings, and why couldn't I work a 9-5? When I went through the fire academy her complaint was that I was gone all day every day and she only saw me for a couple of hours in the evening. Now that I'm working 24's, there's no issue with us.
Anyway, if you have to worry about your spouse double dipping and vice versa, what kind of person did you marry? Jealousy and insecurity is something you need to pick up on much earlier in the relationship. I've dumped many a bunny boiler or high maintenance control freak/princess.
BTW, LA City has used the 48/96 with general satisfaction per their report:
http://www.uflac.org/files/UFLAC 48-96 Color Primo v1.3.pdf