Hi there Wendy,
Your son is going to absolutely LOVE spending his 8th birthday at the Disneyland Resort and even though you're not staying on property you will still be able to have an incredibly magical experience! Disney offers complimentary celebration buttons for guests to wear on special occasions including birthdays! Be sure to stop by any guest relations window to pick up a "Birthday" button that he can wear to get some extra special attention on his special day!
I also suggest booking a character dining experience for him, probably for breakfast! If you're planning to visit California Adventure, I recommend either the
Surf's Up Breakfast at PCH Grill in Disney's Paradise Pier Hotel or Chip and Dale's Woodland friends breakfast
Storyteller's Cafe in the Grand Californian Hotel. You are welcome to dine at both of these restaurants even though you are not staying on property and if you choose Story Teller's, it's only a short walk from California Adventure!
Since your son is turning 8, I think he'll be totally fascinated by Cars Land. You definitely won't want to miss Radiator Springs Racers and perhaps a hearty lunch a Flo's V8 Cafe will get his motor running!
Best Wishes,
Amanda F.