hello Toni and welcome to the Dis Boards!
AKL or the Beach Club?? wow .. a really tough choice. I have stayed at each several times and love each one for different reasons.
What time of year are you going? Are your kids pool lovers? While the pool at AKL is great, Storm a Long Bay at the BC is the best pool at WDW. There is a sandy beach and very shallow play area for the little ones and your older one would love the slide.
One factor that sways me to say BC for you is that it is your first trip. The parks are much closer. You can take the boat or walk to Epcot and MGM. There are so many restaurants very close. The Boardwalk is right across the lake and a fun place to visit.
I love the AKL, don't get me wrong, but it is a different experince, IMHO. It is not so much in the center of things and the eating choices, while very very good, are not as wide. We choose the AKL when we are not planning many park days as it is a wonderful place to relax.
Which ever you choose, have a wonderful, magical time! Visit the other one (and other resorts) for a meal and just see if you like it .. maybe you will find the perfect place for your next visit!