Well I would have suggested the Reagan Library, not all that far away.
Monterey is only about 6 hours IF you drive 101 the whole way. But if you drive 1 between San Luis Obispo and Carmel you can add about two hours assuming good weather. BTW , Carmel is a great destination and I would recommend driving up Highway 1 or at least driving down to Hearst Castle and back one day. (I just spent my vacation at San Simeon State Beach and Limekiln State Park in Big Sur. so I made the trip between Cambria and Monterey about 3 times in a week and a half)
101 takes you through Steinbeck Country, King City, Salinas. From Carmel you're within easy driving distance of several interesting places. The Roaring Camp & Big Trees Railroad is a narrow gauge railroad that runs from Felton (by Santa Cruz) into the Redwoods, San Juan Batista is a small town that has maintained a lot of the buildings from the 1800s and has a variety of nice watering holes and shops.
If you take 1 driving North puts the driver on the scenic side, but you really have to watch the road. South lets the passenger see the views and driver concentrate on staying alive.
If you have the time stop at both Limekiln and Julia Pfeiffer Burns State Parks. At Limekiln take the hike (about 3/4 mile) from the parking area up to the Limekilns and Waterfall, a nice easy hike into some real nice redwood groves. We also saw Blue and Killer whales from the turnouts just south of Limekiln several times.
At Burns take the hike out to the overlook, or stop at the turnout just north of the entrance to see the waterfall.
this is the only place on the coast a waterfall falls right into the ocean.
If you go south to Hearst Castles just about 4 miles north of there is the Elephant Seal rookery on the beach at Piedras Blancas and the herds of Elephant Seals should be coming ashore in November. Ano Nuevo State Beach just north of the north end of Monterey Bay is also an Elephant Seal rookery, but may need reservations. Piedras Blancas is right at a turnout on the highway.