Helen,
Welcome to Team Estrogen! And welcome back to the world of cycling.
OK, so what kind of bike should you look at? Hmmm, the possibilities are endless!
Since you say you want to ride relatively short distances around your local park, and don't plan to go off road, you might take a look at Hybrids or comfort bikes. They have a more upright seating position than a typical road bike, and they usually have wider tires than the road bike, which can come in handy if you want to venture off a paved trail.
If I were you, I'd try a road bike, a hybrid, a comfort bike, and maybe even a mountain bike for the heck of it. It's your $$, enjoy the shopping and buy the bike that you feel the most comfortable on!
I'm sorry that your local bike shop is not very welcoming. I'm fortunate to live in an area where there's lots of nice bike shops. The one I frequent is called Chain Reaction, and they have several articles on bike shopping that you mind find interesting.
http://www.chainreaction.com/hybrids.htm -- an article about Hybrids.
http://www.chainreaction.com/buyroad.htm -- an article about shopping for Road bikes.
They're a Trek dealer, so that's mostly what you'll see on their web site. The info is applicable for other bike brands, and there's several bike brands that will offer a good product for a reasonable price.
Like clothes, different bicycle brands fit differently. The most important part is to get a bike that fits you properly.
Hope this helps! Happy shopping!!
-- Melissa