San Luis Obispo County (or more accurately, just south of Morro Bay) was my stomping grounds for 20 years. I know that part of the coast pretty well. 
First, I’m sorry to say you’re going to be doing the Big Sur drive at the worst time of year.
In July, Highway 1 is packed with tourists and you’ll be ass to elbow following every RV doing about 15 MPH almost the whole time. Very often in summer when it’s hot inland, the fog sucks up against the coast and you can’t see a damn thing. But if that’s when you can go then it’s when you can go. You will still enjoy it, I’m sure.
Sure fire jaw-dropping spot to stop for lunch and a view (assuming the fog isn’t obscuring it) is Nepenthe. Expensive, but you’re buying the view.
If you can stop in Limekiln on your drive south from Monterey, there’s a fine little hike through the redwoods to a (can you guess?) lime kiln. Keep a sharp eye after passing Lucia. The turnoff comes up quick and you can easily miss it. Nice place to walk off some of that lunch you had at Nepenthe. 
Hearst Castle is next, but be advised the tour will take at least a couple of hours and at that time of year, you may have to wait for an available tour time. Crazy place but worth the tour if you haven’t seen it.
Personally, I’d book rooms in Morro Bay and make that your base of operation to explore. You’ll have easy access to the beach and other areas of interest. San Luis Obispo is only about 13 miles away and an easy, pretty drive down Highway 1.
Things to do in Morro Bay:
Go kayaking on the back bay. There’s a spit of land between Morro Bay and the open ocean that makes for easy, scenic kayaking. A fine adventure!
See if you can spot the Peregrine falcons nesting on Morro Rock. Take a picnic and spend the day building sand castles on Morro Strand beach. Or if you’d rather not fuss with a picnic, there’s no shortage of seafood restaurants along the main street.
Things To Do in SLO:
Yes, the Farmer’s Market on Thursdays. Try not to miss. Partake of the Santa Maria-style barbecue tri-tip sammiches. You’ll be delighted at the quality of the musical groups that play regularly there. Very festive and fun.
Don’t miss the Mission de Tolosa downtown, an easy and worthwhile place to explore. Outside the Mission, it’s a lovely ramble all through the downtown area and adjacent to the creek. The whole town is a boutique.
If you like Italian food, San Luis Obispo is your kinda town. It was largely settled by Italians and the influence is a happy one. I can unreservedly recommend Buona Tavola for lunch. They make a hearty salad (insalata alla tosca) that I still dream about. It’s next door to the Fremont Theater, a short walk east from the Mission and across from the courthouse. You can’t go wrong.
The other big draw in SLO is the Madonna Inn. Not my cup of tea, but if you haven’t seen it, it’s worth a quick look-see. Located just off 101 as you head south. It’s different. Don’t stay there, just look around.
Hidden Gems in SLO County:
Montaña de Oro State Park. You can walk along the headlands (do keep a sharp eye for rattlesnakes sunning themselves on the path) or explore the eucalyptus groves. If you time it right, the Monarch butterflies stop in the groves on their migrations, thousands of them. Quite a sight. But even without Monarch butterflies, Montaña de Oro is hidden and special. The locals won’t appreciate me mentioning it.
Sycamore Mineral Hot Springs. You can book a private hot tub and enjoy a soak in a truly lovely setting. If you’re feeling stressed, book a massage, too. Most restful!
I’ve got more if you want it, but this is already long enough.
Happy exploring!