I'm with Vintage Schwinn on the choice for a cruiser, however, finding a Chicago made Schwinn that doesn't need something for a reasonable cost will be challenging. They are simple enough to work on however, I don't get the impression that you are not looking for a project. If you are up for it Vintage Schwinn cruisers are blue chips. We can help you through a project.
All the bikes that you mention, @
Muddydog are good bikes. The Townie that is in your family is a good bike, but keep in mind that is a "Foot Forward" bike. You may like this style, you may not. If you do maybe, it is worth fixing up what you have rather than getting something else that may also need a few things.
I'm also concerned since you are near the beach. Here on Fire Island, Long Island there are lots of cruisers. They are all rusty because of the salt air. No matter what you get, it may be damaged from the environment. You may want to consider a La Jolla from WalMart or other big box store. I know that it is blasphemy around here, getting a department store bike. And it is not as good as the ones that you mention above, but it will rust and you won't worry about it. Just ride it. When it gets too bad, get another one. The frame is aluminum, but the rims, handlebar and other parts are steel and will rust in time. Whether it is a Jamis, Electra, Schwinn or Kent you are likely to be dealing with rust.
La Jolla at Walmart