Paul Klee, the more well known of the two, was a prolific artist with thousands of works of art produced over his lifetime. His style also changed significantly through his career. Ivan Aguéli, on the other hand, was much less prolific in his creation of art. In fact, only four works of art were ever exhibited (as part of a larger exhibition) during his lifetime.
Moderna is located on the island of Skeppsholmen. The easiest way to get there from the Rival Hotel is by taking the Djurgård ferry from nearby Slussen. When you go on to the ferry, let the staff know that you wish to disembark at Skeppsholmen (otherwise they will not make the stop). Moderna is one of the museums that has recently started with free admission.