My advice- after taking many a group of out-of-town relatives to Disneyland.
Because you have little ones
Take a sroller ( they rent them, but $$$$)
Take snacks
Take inexpensive toys ( something you can afford to lose) to keep everyone entertained while in line
Go to one of the character breakfasts, (make sure to ask which character will be joining you- you don't want anybody bursting into tears when they see Tigger ) and seat the little ones nearest the aisle.
Buy the photos, even if you're taking your own (grandparents will go crazy)
Mousesavers