Hi Jessica,
A lot depends on your budget. Look at the various Disney resorts
HERE . Depending on which price range you are interested in staying in (Value, Moderate or Deluxe) I can help you choose a resort.
With children ages 5 & 7 you'll want to definitely spend a full day at the Magic Kingdom. For your second park, personally I would choose the Animal Kingdom. My youngest two are 6 & 8 and it has been their favorite park for years. They love all of the nature walks, the Kilimanjaro Safari and much, much more.
Do you only want to visit one park per day? If so, just purchase Base Tickets. If you think you'd like to spend half a day at Animal Kingdom and another half day at Epcot (for example) then you'll need the Park Hopper tickets.
Once you decide on your resort category, you can reply to me directly and I can help you choose.
Have a wonderful vacation,
Kaylene