Hi Alicia,
As the mom of two boys close in age to yours, I can tell you that you will likely be tired long before they "hit the wall!" If you are on a tight budget, I would consider sticking with the Magic Your Way Base Ticket. This ticket would allow you to visit one park as many times as you like in a single day. You could take a break mid-day, return to your resort to swim, have a meal outside the parks and come back for some evening fun, rides, fireworks, etc. This "system" works well for my family. We head out early in the day, and then go back to our resort when the crowds and sun are at their peak for a break. We come back later on refreshed and with a second wind. The cost per day of all of the tickets actually goes down as the number of days increases, so if I had to chose, I'd go with a longer number of days over the park hopper option.
If you are planning any time off-site, or think that your kids would like a day away from the parks a shorter day ticket is certainly an option. (You could always upgrade to include more days if your plans changed.) At Disney, there are a large number of options for your family outside the four main theme parks that don't require admission. Your resort pool, the Boardwalk and Downtown Disney are all great options. The Boardwalk has roving comedians, magicians and surrey bikes available for rent. Downtown Disney has one of the most elaborate Lego stores in the country and an outside playground.
If you would like additional information about theme park ticket prices and options, feel free to click
HERE. Have a great trip!