We have 2 full days in Capri this spring. I was hoping I could get advice on how to plan our time?

We would like to order sandals, visit Anacapri (chair lift, San Michele), boat tour, enjoy scenery/short hikes, EAT! Our flat is near the main piazza in town.

We plan to book a private boat trip around the island. The water will be too cold for our tastes, so do not plan to swim. Will the 2 hour trip suffice? Or should we look at a 3-4 hour that could include lunch somewhere else on the island we would not otherwise be able to easily visit? We want to visit grottos, learn history of island, enjoy a few drinks, etc. I don't mind paying a little bit more for the extra time on the water if it will be time well spent.

Thank you in advance.

When in spring? Some specific dates would help as March and May have very different weather in this area which could influence your boat trip plans

Yes the Blue Grotto can be unreachable by boat at high tide or in some kinds of weather - like when I was there it was closed though we could see it from the outside and sea was calm - hop on that the first day if open.

The Blue Grotto closes in rough weather - it's not tidal. Even if the winds are high, causing the sea to be choppy, it will close as the archway entrance is so small you have to lie down in the rowboats to get inside. The Blue Grotto is expensive. It's 12 euro for admission and about 12-15 euro for the rowboat guys - and they demand a hefty tip (the 'no tipping in Italy' culture does not apply here!
Your private boat will take you to the Blue grotto, you then have to pay the admission plus the boatman so you're looking at around 30 euro each.

we will be there mid-April. My plan is to make reservation for boat tour on our first day, just in case weather is too rough we have the second day as a back up.

Your boat trip will depend on tne condition of the sea. There are frequent boats tours around the island that hold a large group of people. I wouldn't have wanted to be on a smaller boat than we were. Our hotel let us know when it was finally OK for us to take a boat around the island as the sea calmed down.

We did a boat tour for about 3 hours, but I think 2 hours is really sufficient. Especially if you are not stopping at the Blue Grotto. We had wanted to but it was closed that day as the water was too high for the entrance, so we just toured around the island. Nice tour but again I think 2 hour is enough.

As for sandals, there is a really good place right down at the marina, my wife had sandals made there and really loved them. When you get off the funicular from the Piazzetta, it's just there on your left. The sandalmaker is right outside the store, just go inside and pick out what you want.

Enjoy your trip, we spent 3 nights there in September 2014 and really loved it, highlight of our trip and you'll be glad you are spending time there instead of just a day trip. It's magical at night! Check out Aurora, one of our favorite restaurants there.