Talk to an attorney about what is reasonable in your state.
In my state, the rough norm is alimony for half the number of years you were married (if alimony is appropriate). Lifelong alimony would be unlikely unless you were disabled. (Perhaps if you had never ever worked and you H had a boatload of money, but otherwise, no).
Also in my state, alimony is always subject to revisitation; that is, if HIS financial circumstances change, like he gets fired or becomes disabled, he can petition the court to reconsider his alimony obligation.
So, for instance, in my case, my ex wanted to reduce the number of years of alimony from 12 (1/2 our marriage) to 10. I agreed to it because I knew that he would be eligible for early retirement from his job in 10 years, and could probably get the alimony reduced or removed at that time - and when he DOES take the early retirement, I get a portion that is equivalent to the alimony anyway (I did negotiate this away for something else that I wanted, so I see it as a win.)
In your case, you may want to try to get the alimony continued to whatever your social security retirement age is ( probably 66 or 67 years depending on your birth year). Then at least you will have that income to replace the alimony. If you have been married for 10 years you can claim the spousal benefit based on his social security if that will be more than the benefit based on your own earnings.
If there are enough assets to make it financially feasible, you may want to consider taking a lump sum instead of alimony. I wish this had been feasible in my own divorce. My ex (who is not good with numbers and budgets and taxes, etc) has apparently been laboring under the mistaken impression, for 7 years, that he is paying 1/4 of his income to me in alimony. The real figure is 11% once all taxes are taken into account. Much of his bitterness in the past few years has apparently been about writing that check every month! And unnecessarily so, because he didn't understand the true figures. If we had been able to negotiate a lump sum in the beginning, that might have been better. Also you need life insurance on him that will pay his alimony and child support obligations if he dies.
Child support is usually by formula. Depending on your state, you may not be able to do any better than what the formula gives. You will want to write in stipulations for other things though, like funding college, paying for childcare and extracurricular activities like summer camps etc.
Keep in mind when you negotiate the tax implications of various choices too. He gets to deduct alimony from his taxes - you pay taxes on the alimony income. On the other hand, if you get a lump sum settlement at the time of divorce, there are no tax implications for either of you. Child support is not taxed.
What is best for you depends a lot on your particular situation and your earning capacity as well as your assets and your need for cash at present. If you're not good with math and taxes, find a friend or financial counselor who can help you work through various scenarios. (For the record, your lawyer may not be very helpful with this - I definitely was more savvy about taxes etc than my divorce lawyer, although he was great in other ways.)
