My first stop in Tarragona is Jumpland Aventura Ecològica. It was such a good experience that the whole family can enjoy, from children to grandparents. The routes have easy, medium and difficult with zip wires at the end that are my personal favourite.
You can choose which type of activity you want with different prices. I found the guides very helpful and were very safety conscious and will translate in English if you need them to.
The second stop was Cambrils which I would advice for the people who enjoy the quieter seaside towns. You can take a road train ride through the town which takes 40 minutes and shows you some of the highlights of the town.
There is plenty to keep you entertained with plenty of restaurants, bars and excursions during the day.