DH and I knew before we had kids that I would be a SAHM or work just a few hrs a wk. If I had a job I really loved, I would have tried to work PT, but I hated my job, so becoming a SAHM was not a burden to me. We have cut our, going out to eat costs and entertainment (going to the movies, etc.) cost a LOT since having joshua. We cook in more often, I've always been a frugal grocery (I don't mind buying generic either) and other things shopper, so that was never an issue. I cancelled my cell phone and now I just have a pre-paid cell phone, more for emergencies, and quickie calls, etc.. Cancelled our land line's long distance, I just use DH's cell phone as much as possible and we have a sam's club calling card too, which is really cheap, like 3 cents a minute. Also, when we bought our current house, we did not factor in my salary, we only budgeted for a house with DH's salary knowing that someday I'd be a SAHM and my salary would not be there for everyday costs.
Also, for family vacations and stuff like that, we plan vacation around trips we have to make anyway. Like DH's work conventions, or friends' weddings, etc.. That way, we are already going there for a specific purpose, we just stay a few extra days, which isn't a huge cost difference. I know this means we don't get to go anywhere exotic, but it still counts as a vacation for us, plus my DH makes good use of his vacation time this way.
We also made sure that many of our debts (college loans and credit cards) were paid off before we started a family. Our cars are all paid off, except for one, so we only have one car payment and our mortgage. We pay off our cc bill in full every month, so we do not have to pay any interest. I make it sound like we don't do anything, but we actually have nice stuff. I just really shop clearance a LOT, and my DH no longer questions my ability to find GREAT stuff at deep clearance prices, in fact he has picked it up himself (his latest find was a really nice colored laser printer for $150 open box, that was orig $600... it had some problems, so he called CS, and minolta/konica sent him a brand new one to replace it!). We also splurge on DSL, a digital dish and netflix, but skimp on a lot of other not so important things.
Anyway, I will eventually have to return back to work when the kids are older, in order to save for their college costs and also to put $ away for our retirement (although, I think our generation will NOT be able to retire).