If you have the opportunity, there is no doubt that the best branch of hospitals to volunteer at is their hospice program. I can speak from personal experience, and have heard nothing but the same from others.
It is truly HANDS ON--the closest that I am aware of in any hospital wing. Every night, I am either sitting with patients and just chatting, or helping the nurses do bed changes, repositioning, giving medication, etc. The other week, I was in a room where an individual that was on a ventilator got into trouble, and I spent a good 45 minutes breathing for him with a manual bag while two RN's tried to figure out what was wrong. Like I said, hands on.
In addition, you are around the same six or seven nurses often and build great relationships for references (I am assuming this is common everywhere). I have never left there after volunteering without being lifted and feeling not only like I made a difference in someones life, but that they shaped my own as well. It puts things in perspective and is WAY more than just another volunteering experience.
I encourage everyone on here to give the local hospice house a try if possible. I think others that have done the same would agree with me.