an idea is getting a "comfort" bike, or a hybrid style bike, they are often relatively decent pricing and good quality. a couple examples are:
specialized:
http://www.specialized.com/bc/SBCBkModel.jsp?spid=32563
http://www.specialized.com/bc/SBCBkModel.jsp?spid=32296
giant:
http://www.giant-bicycles.com/en-US/bikes/lifestyle/
cruisers are also good bikes for well, cruising, nice relaxing rides.
on the specialized site you see msrp's around 360 - 500 usd but if you go to a local bike (or sporting goods) store you can usually get last years model at a seriously discounted price (for example my mother in-law got a specialized comfort bike for 250~)
hope this helps some
-john