Seal Beach doesn't attract any more seals than the average SoCal beach. You might spot some there, but you probably won't. The best beach for seal watching isn't in Orange County, it's down in San Diego at the La Jolla Children's Beach; except the seals and sea lions took over a few decades ago and the children don't get much chance to get into the water there because the seals are in the way.
Tide pools? That's easy much closer to Disneyland. You'll want to head to Crystal Cove State Park, which is about a 30 minute drive from Disneyland and on Coast Highway between Newport Beach and Laguna Beach.
You park in the State Park lot up on the highway, and then hike down a short trail down the bluffs and to the beach area. There is a broad sandy stretch, but south of that is the tide pool area and it's very accessible to get to with kids. The park rangers are there during peak seasons to offer info about the sealife you see in the tide pools, and it's just a nice place to spend the afternoon.
http://www.crystalcovestatepark.com/
If viewing the tide pools is important to you, you'll want to consult the tidal charts close to the day of your visit as you'll obviously want to time your visit as close to low tide as possible. At high tide the tide pools are largely inaccessible or underwater.
Crystal Cove State Park - 30 Minutes From Disneyland
As it's a State Park, there are no real dining or tourist amenities in the park aside from restrooms and the usual State Park information boards and a Ranger Station. For food before or after your visit to the park, you can head a few minutes north or south on Coast Highway. Very close to the park is a famous locals hangout, the Shake Shack, where surfers and families stop for delicious handmade shakes, cheeseburgers, and tuna sandwiches. It's got a nice patio on the cliff with a million dollar view of the Pacific Ocean, all for the price of a $5 milkshake.
A couple miles further south on Coast Highway, and you enter famous Laguna Beach. It's artsy and a bit funky, but definitely upscale. Lots of bistros and cafés and fancy restaurants can be found in Laguna Beach, amidst the art galleries and boutiques in the downtown district and/or along the Coast Highway maid drag.
If you want to find a place suitable for children, a great option is south of Laguna Beach's main business district at the Ruby's Autodiner. All-American road food and burgers, but done very nicely and with great quality in a fun diner theme.
http://www.rubys.com/
By the time you got to the Autodiner you are now really in South Orange County on Coast Highway, and it would be about a 45 minute drive back to Disneyland taking into consideration the slower speed limits of Coast Highway and the stop lights in Laguna Beach and Newport Beach before you could get back to the freeway to speed you inland to Disneyland. But it's a great day trip from Disneyland that you can spend anywhere from a few hours to an entire day on if you want.