Hello,
Diablo islands in San Blas is owned by my Kuna Family friends. The islands is nice and well situated. There is a shipwrek in front of the island for snorkelling. I have been several time since 2007 in San Blas and I always stay in Diablo with my friends. Pelicano is one of the first islands that you can reach from the port, it is nice but then they will offer you a tour to go to the shipwrek which stands in front of Diablo. They will also bring you to the starfish islands as it is included in their day tour. I would not "run" to different islanfs in one day. This is heavy. Leaving 5.30am for your hotel in Panama-City arriving 10am at the Barsuku port, boat ride, arriving 11am in the San Blas islands (i.e Diablo) back from Diablo to the Port around 4pm to finally arrive in the city at 7.30pm. It is a shame you cannot stay one night but you will still enjoy it.
Best regards from Panama.