Welcome to planDisney Katherine!
I am not sure I have ever thought "too much Disney!" Is that even possible?! But as a fellow "mom" I totally understand your concern!
Let's start with the Disney Cruise as a stand-alone. I always suggest driving/flying into the Orlando or Port Canaveral area a day prior to boarding. This allows for any flight or traffic delays and takes away stress.
If you are planning a
Walt Disney World/Disney Cruise combination, I prefer land first, then sea. The cruise is a nice way to relax after a few active days in the parks.
I actually like your plan of a few nights at
Disney's Beach Club. You are just steps away from EPCOT, as well as the
Disney Skyliner that will fly you over to Disney's Hollywood Studios. Bus service is available to Disney's Animal Kingdom and the Magic Kingdom.
The important thing is to not push too hard on your park days. Maybe don't park hop and choose just one park each day. Or, take a nice mid-day break at your resort between parks. The Beach Club has (in my opinion!) the best pool on property - Stormalong Bay. Your kids are going to love it, so take time to enjoy it!
Another tip is to bring a
stroller for your little ones, especially your 3-year-old. This will keep little legs from getting too tired with all the walking! With 4 kids, you will also appreciate the stroller to store your tote bag, hats, water bottles, etc.
Whatever you decide, plan for plenty of breaks and keep to a regular bedtime to avoid anyone (including the grown-ups!) from getting over-tired. After a few fun-filled park days, go enjoy some time at sea with Captains Mickey and Minnie. What a magical vacation combination for you and your crew. Bon Voyage!
Cathy