Hi! We did something very similar in Mallorca, and the coast that really stood out for a boat trip was the northwest coast toward the Serra de Tramuntana (near Sóller/Sa Calobra). The landscapes are much wilder—cliffs, super clear water—it’s quite different from the rest of the island.
We also tried a half-day on the east side (near Cala d’Or), which was pretty but more "postcard-like" and busier. For renting a boat, we looked at several options, like Click&Boat, SamBoat, and GetMyBoat.
Another thing we loved: you can also spend a day in Menorca by boat—it’s a completely different vibe, even quieter and wilder. To check routes and options between the islands, we used Ferry Hopper, here.