As mentioned, hospital visits can be tricky, not just due to privacy and safety, but other sanitation and health concerns.
That said, a lot of people get in to costuming with an eye on doing more than just treating every convention like it's Halloween. Hospital visits aren't the only avenue for using your costume for charity work. We see a lot of clans going out to support blood drives with the Red Cross, school/library visits on Star Wars Reads day, walks for cancer or diabetes, troops at the Special Olympics, and so on.
Depending on how far out in the boonies you live, you might see if there are other Star Wars groups in your area like the 501st, Rebel Legion or Dark Empire, and network with them to get together for a Star Wars day or something. You might also see if there are other non-Star Wars groups around who do charity events in your area and see if you can hook up with them. That way, when you show up in your costume, you're not just a strange guy who says, "I want to visit with sick kids"; you're there with three Ghostbusters, the Witch King, a couple of Power Rangers, Mario, a Biker Scout and Batman.