If your kids are chronic whiners, maybe it's because you're setting them a poor example of contentment. If you want a happy household of happy people, make a point of regularly emphasizing the following principles and living by them yourself.
If you're thinking that a change in your income or family situation would make it easy for you to live happily ever after-I can guarantee that it wouldn't. If you're habitually unhappy with your current situation, a major part of the fault lies in your own attitude; and until you change that, your satisfaction with any betterment of circumstances will last only until the first new stress point.
Misery loves the company of such phrases as "Nothing ever goes right for me" and "I always get all the bad breaks." Unless your goal is to invite more misery into your life, purge your spoken and unspoken vocabulary of such talk.
Kids are naturals at enjoying life even when circumstances are disruptive (remember the thrill of an unexpected bad-weather day off from school?); but unfortunately most parents succeed in teaching the lesson that plans and duties are to be jealously protected, and any change in them is an abomination. Next time your grade-schoolers react with an "Oh, boy!" to a flood day or a freight train crossing your path, consider not responding with a growled, "But it's such a nuisance." Forget your own to-do list (and imminent readjustments) for a while, and let yourself get swept up with the kids in the pleasure of the moment. When time comes to make up for the delay, you'll find yourself much better equipped to do so effectively.
Many people make the mistake of seeing it as an either-or situation: being content with the present means sacrificing all incentive to work for a better future. Again, we can learn (or re-learn) from our children's natural instincts. For the young, it's easy to believe that "life is good but there's even better to come," because they're intimately aware of learning and growing as everyday matters. You don't have to lose this attitude just because you've officially "grown up."
Most people's "goals" stop at getting more of what they already have: more money, a bigger house, more influence, bigger muscles. Why not set your sights for broader horizons? Take a course on a new-to-you topic, explore a different career option, rediscover an old dream. Put some adventure into your days and find the joy in becoming more than you thought you could be!