You can skip the Skypiea Arc if you'd like, but it's worth noting that the arc introduces important characters and plot points that may become relevant later in the story. If you're short on time, you can find summaries of the arc to ensure you don't miss any key information.
While technically another filler arc, the G-8 Arc at least functions as an epilogue to the Skypiea Arc. After Luffy and the crew crash-land on the Earth, they find themselves in the custody of the Marines in their base and desperately need an escape.
