Advice on beach and hiking in CT

...should we ferry to Corniglia and hike to Vernazza

The ferries don't service Corniglia as it doesn't have a proper harbor. You'll need to reach this one by train or on foot. To reach the village itself by train, you'll need to climb a very long switchback stairway or take a little bus up the hill.

Should we do hike in am and beach afternoon?

In July? Yes. Afternoon hiking would be very warm and the trails you mention would probably be at their most crowded.

On the hike from Monterroso to Vernazza, has anyone used the shuttle
bus to avoid the steps at the beginning (mentioned in RS book)?

I'm personally unaware of busing to avoid the steps mentioned but, well, the steps ARE the trail so if you want to hike it....

Neither the hike Monterosso>Vernazza or Vernazza>Corniglia will take entire 1/2 days. On the day you do Vernazza>Corniglia, I would catch trains onward to see Manarola and Riomaggiore and then return to Monterosso by ferry.

Thank you, Kathy. I had forgotten that Corniglia is not on the sea so I will need to take the train.

I love your plan! - On the day you do Vernazza>Corniglia, I would catch trains onward to see Manarola and Riomaggiore and then return to Monterosso by ferry.

A note about La Spiaggia (which we've stayed at)? Mr. Andrea (Poggi) has sadly passed but guests dripping sea water across his lobby used to drive him nuts. LOL, I'd read the comments from the unfortunate few who'd caught holy you-know-what from him for that! Besides making a mess, it was a slipping hazard for others so he had his reasons. His daughter, Maria, would likely be more forgiving but, well, dry off good and wear your shoes when traveling from beach to room? :O)

Maria, BTW, is a treasure, and her dad - who was a wealth of local knowledge - is missed amongst regulars to this family-owned property.

Kelly,

Could you clarify why you're planning to use the beach at Bonassola rather than Monterosso or one of the other towns? There's also a large beach in Levanto.

A few thoughts.....

If you arrive at 15:05, by the time you've checked into your hotel and prepared for the hike, it will be late afternoon. That's probably not the best time for a hike.

Option 2 seems like the best one. Regarding the "sunset cruise", as I recall the Ferries stop operating in the late afternoon. However you could certainly hire a private firm for the cruise. This is one tour based in Monterosso - https://www.angelosboattours.com/ .

I just wanted two beach options. Monterossa is first choice especially with our hotel right there. Since the other CT towns do not have beaches or not nice beaches, RS recommends going to Levanto and renting a bike to ride to Bonassola. He says the beach is jewel and mentions it twice in his CT section. Just another option. We are not big hikers, but we could handle a 10 minute bike ride. However, I was just reading that the bike shops take a large siesta so I’ll need to make sure I have my ducks in a row if we choose to go to Bonassola. We could walk the path also. So many possibilities that my head is spinning. I think it’s one of those times when we will just plan as we go along which is hard for a super organized person like myself,

Are you arriving from Milan direct from the US? Or are you staying in Milan after arriving from US and then going to Monterosso another day?
If coming straight to Monterosso from US I would not recommend this hike. It will be late, you will be tired, jet-lagged. Why not just explore Monterosso then, go to the beach, etc. You can always hop on the train to Vernazza or one of the other towns, each about 5 minutes apart from each other if you wish.