At San Juan we did the Old City Walking Tour. Way too much information. It was Spring so it wasn't too bad. I would NOT recommend doing this in Summer (June-September). The streets are cobblestone which is NOT good for older people or anyone with knee or back problems.
In St. Kitts we took the tour of Clay Plantation which was excellent. The animal refuge was clean and provided safe spacious rehabilitation for the animals. The rum punch was amazing and the fruit punch was fresh and quenched thirst. Part two was Frigate Bay Beach. It was the WORST beach ever. There were sharp jagged rocks in the water and many people had their shins torn up. There was only ONE changing room and it was filthy. If you can take a tour of just the plantation, I would recommend it, but avoid Frigate bay Beach.