The Legoland part you've figured out. And the going-to-the-beach part. But once your family has set its sights on a quick, kid-friendly trip to northern coastal San Diego County, there's still the question of where to sleep.
Here's a round-up of several non-chain options in this little city -- all west of Interstate 5 and the railroad tracks, all handy to the Pacific, all within easy range of those thousands upon thousands of colored plastic building blocks. Bear in mind that there are plenty of major-chain lodgings as well -- including the new Sheraton Carlsbad Resort & Spa -- and there are a few other things to do besides Legoland and the beach.
There are the Flower Fields at Carlsbad Ranch on Paseo del Norte. The season has just ended (it runs from March 1 through early May), but the city has many other things to offer.
Downtown Carlsbad includes a train station, the Carlsbad Mineral Water Spa (a three-story Bavarian haven of mineral baths and mud facials), the Witch Creek Winery tasting room, the big Victorian Ocean House restaurant, a Starbucks and the Fahrenheit 451 used-books store (good selection, heavy on Beat writers but unpredictable hours). Most of these are lined up along Carlsbad Boulevard (a.k.a. U.S. 101); others are perpendicular in Carlsbad Village Drive. (More information:  227-5722, www.visitcarlsbad.com.)
Among Carlsbad's lodgings:
Carlsbad Inn Beach Resort, 3075 Carlsbad Blvd.; (760) 434-7020 or (800) 235-3939, www.carlsbadinn.com. This four-acre compound combines lodgings and a mini-mall, with the biggest buildings (except for the Mexican restaurant) done up in Tudor style. There are 62 hotel rooms, many with kitchenettes, and rentable time-share condos, a grassy courtyard, pool, pingpong, Jacuzzi-style tubs, Norte's Mexican restaurant and sun-splashed Daily News Cafe, for breakfast and lunch. To reach the beach, cross Ocean Street and descend a staircase -- perhaps 50 steps. I'm not a fan of the architectural style, but the family-friendliness is formidable. Next time I head this way, this is the first place I'll call. Rooms have kitchenettes. As a walk-up customer on a spring weekday night, I negotiated a $169 rate for an ocean-view room. Rack rates begin at $195. For the 132 condos (120 one-bedrooms units and a dozen two-bedroom units), summer rates, now in effect, are $239 to $399; off-season rates run $149 to $399. For condo reservations, call (877) 477-7368 or see www.resortime.com.
Tamarack Beach Resort by the Sea in Carlsbad, 3200 Carlsbad Blvd.; (800) 334-2199, www.tamarackresort.com. This place, which includes 23 hotel rooms and 55 rentable condos, sits across the street from the beach and a popular waterfront jogging path. Outside, there are barbecue grills and a courtyard swimming pool squeezed between buildings. Inside, you'll find pool tables and a handful of video games and a big fake billfish leaping over a fireplace. Off-season hotel-room rates run $169 to $199. Summer rates (beginning June 15) are $230 to $270. The condo units (which include kitchens, dishwashers and washer-dryers) go for $248 to $416 daily.
Best Western Beach View Lodge, 3180 Carlsbad Blvd.; (800) 535-5588, www.beachviewlodge.com. The Craftsman-style facade will catch your eye. Stepping in, you'll find the well-tended building beyond it less stylish, built in the boxy '60s beach hotel/apartment tradition. Still, there's a smallish oval courtyard pool and whirlpool, an upstairs deck with a nice view, and the beach is just across busy Carlsbad Boulevard. Three stories, 41 rooms (some with balconies) and six suites with kitchenettes and fireplaces. Off-season rates $170 to $225, summer rates (which began May 16) $185 to $240. Auto club discounts of as much as 15% are available. (And if you're wondering why Best Western is included in a list of "non-chain" restaurants, bear in mind that Best Westerns are independently owned and operated. Some get three-diamond ratings from the auto club, some get two, some aren't rated at all. The name Best Western means only that the operators have agreed to work together on marketing, reservations etc.)
Ocean Palms Beach Resort, 2950 Ocean St.; (888) 802-3224, www.opbr.com. Although it looks quite retro-tiki-trendy from the outside, it's more humdrum from inside the standard units. They all have kitchens, though, and the beach is a block away. Fifty rooms. Off-season rates $114 to $400, summer rates (which kicked in Tuesday) $189 to $515.
Beach Terrace Inn, 2775 Ocean St.; (800) 433-5415, www.beachterraceinn.com. The inn offers 49 rooms, most of them one-bedroom suites, some with ocean-front views, almost all with at least partial views of the Pacific. Though the lobby has just been given an ultra-cool design makeover and the inn sports a tempting triangular pool a few steps up from the beach, many of the rooms are still outfitted with basic (some would say motel-style) furniture and fixtures.