For those of you who are local, you may be familiar with Myrtle Point Park.
This park offers a perfect hike for families with young kids that loops and has a few offshoots for visits to the beach. It is approximately 2.7 miles. We brought cheese and turkey wraps (for us veggies and the kids who are meat eaters with dairy allergies respectively). We stopped midway to eat, and while we skipped the beach this time, next time we will make a lengthy stop for swimming and catching some rays.
We took Maeryn in our Kelty Kids Journey (got it at REI in the back room on sale for sixty bucks - a bloody steal!) and no day packs. We dropped two diapers, some wipes, and snacks in the back of her pack (comes with a small backpack) and I carried the Camelback - which was super light compared to Maeryn (who I've only done 2 miles with in the past - she's heavy!).
Both kids had a good time, though Maeryn would've liked to get out and walk a bit and we declined on this trip, because it was our first exploration of the trail and we weren't sure how it would be for the baby. Jonah ate the whole thing up - he was the trail blazer most of the way, which really cuts down on the frustration that is created when the four year old brings up the rear. His responsibility allowed him to warn us of pending doom (spiderwebs, a mushroom on the trail, a big rock) and stopped him from lagging to look at said objects.