for first trip i would recommend to allow 2-days at each park. the first day in each park will seem overwhelming, two days will allow you to slow the pace down and really get a good feel for the parks.
This is a really good idea. Take your time. It's important to remember that you won't be able to see or do it all in your first trip even though you'll really want to. Research on the sites and in the books will help you find what attractions/shows are best for your family at this point in time, so you can have a great time without exhausting yourself. As a mom, I know you're busy. Don't forget there are Disney specialist travel agents who can help with some of the big decisions if you need them.