All Uranian moons can be featured (except Umbriel), in my opinion. Exploration of Jupiter is a good idea too. Jupiter Trojans? Little is known about them. However any article can become featured. There were long discussions on Wikipedia_talk:Featured article candidate about notability and minimal length, but they came to nowhere. So if you start working on one of those articles (Exploration of Jupiter or Jupiter Trojans) I will support you. As to Moons of Saturn I think the knowledge about them is very unstable now. New information comes almost every day. It is difficult to write about them.  

 Another my idea is to create Portal:Jupiter.