Greetings Kathleen!
Your first Walt Disney World vacation? How exciting!! You are going to have such a magical time.
I see you are arriving in June. I definitely think adding the Water Park Fun and More Option (WPF&M) to your Armed Forces Salute Tickets is a great idea. Having the option to cool off at either of Walt Disney World's water parks or in the air conditioning at DisneyQuest will come in handy during the warm days of June.
A single day admission to Disney's Blizzard Beach currently costs $52.19 for an adult (ages 10 & up) and $43.67 for those ages 3-9. DisneyQuest passes run $45.80 for adults and $39.41 for children.
So, even if you use only one of your WPF&M credits, you're saving a ton!
If you add the WPF&M to your tickets, you'll have four
days of major theme park admission and four
entries to the WPF&M options. It really extends the fun and gives you things to do on days where you don't want to visit the major theme parks.
There really isn't one good answer on the
Disney Dining Plan (DDP). A lot of it depends on your family and their eating styles. My suggestion is to go look at menus over at a site like allears.net. Price out what your family would eat in a typical day. Compare that price and the amount of food you get on the DDP to your projected amount and see if it really is a deal for your family. We do not use the DDP when traveling as a family. We like to load up a Disney Gift Card each payday and use that towards our meals instead.
I'm running short on room, but please come back and see me again if you have any more questions. I love helping fellow military families plan their pixie-dusted vacations!