Head south out of town up Miguelito Canyon and the fog burns off, the oaks close in overhead, and you're in a completely different Lompoc than the one on H Street. Miguelito is the shady one. Big oaks, group picnic areas you can reserve, a playground, and trails climbing up the canyon walls. It's the park families book for birthdays and reunions, and on a hot inland afternoon it's ten degrees cooler under the trees than it is downtown. It's roughly ten minutes from the middle of town, which puts it firmly in the category of places locals mean to go and somehow never do.
Group areas need a reservation through Santa Barbara County Parks — walk-up picnicking is fine anywhere else. The upper trails get steep quickly; good shoes if you're going past the picnic loop. Cell service thins out in the canyon.