My wife has a 1980 Raleigh 5 speed which is in like-new condition. I seems to weigh about 1000 pounds compared to the aluminum bikes we have. When I hang it in the garage, I have to get help lifting it! She has decided to get a 3 speed cruiser with aluminum frame and components. It has in Shimano 3 speed internal hub.
http://www.sunbicycles.com/03/html_0...alynexus3.html
Ride both and see. I don't think the weight would be critical for the type of riding you describe (I'm doing the same), BUT all of the LBS folks I spoke with said it makes a big differebce and to get aluminum.