Thanks to the help of everyone here we have our San Diego itinerary mostly worked out. We are staying at La Jolla Beach and Tennis club and travelling with a toddler. We have one day with no activities planned (the other 7 days are filled with arrival/beach day, Legoland, Seaworld, SD Zoo, Wild Animal Park, Scripps Aquarium and brunch at Hotel Del). Most of our activities will be in the morning with afternoons reserved for naps and beach/play at resort. Any suggestions for that open day? (We will probably not head to Anaheim as we are frequent visitors of Disneyland or to Mexico).

just leave it open. the number one regret that most of my visitors had was that they had planned too much.

I agree with ltt. I think you have too many activities packed in already, especially with a toddler. You will be doing lots of walking and standing in lots of lines at Legoland, Seaworld, etc. After 2 or 3 days of this, you will probably be thankful for a day of downtime.

You've already planned to have relaxing afternoons so I don't see any reason not to add another place to visit. You could go to the Embarcadero and visit the Maritime Museum and the aircraft carrier USS Midway.Or you could drive out to the Cabrillo National Monument on Point Loma-interesting history and fabulous views, also tide pools depending on your toddler's age. Or you could go to Old Town, the historic part. Or you could drive up into the mountains and visit Julian, an old gold-mining town.

But I bet you stay at the beach!

Thanks for the suggestions. I think we will take all your advice and play it by ear (either a relaxing day at the beach or a drive to Point Loma, my daughter loved the tide pools during our stay on Vancouver Island, or both). This open day falls right in the middle of the trip so it would probably be a good day to not have any specific plans though I do welcome other suggestions or comments. We are so ready for vacation!

To be honest, with some of those days (Sea World, Zoo, Wild Animal Park, Legoland) there is NO WAY you're going to be back relaxing in the afternoon. Think child napping in the stroller. Not that that's a bad thing, just adjust your expectations.

HI..
Just hang out in La Jolla and walk along the coastline and have a great lunch and then come back and just relax either in your room or on the beach.. The Sea Lodge Restaurant is a pretty good restaurant and the view is wonderful.. Go to Jeff's Burgers a block away from the LJBTC and also The Cheese Shop for the best Deli sandwiches and Piatti's is always good too..
Your toddler is going to have a blast making sand castles and playing in the water and the tidepools by the pier at low tide..
Have a blast in our town and give us a trip report when you come back..