The best suggestion I could give you is to leave your wallet and checkbook at home, then go visit your local dealer. They have a lot of bikes, and you can go ahead and sit on them to see if they'd be comfortable. My wife is 5'4", and she can sit on my 86 Virago. If you have the bucks, look at the Harley 883 Huggers.
When it's time to buy, I'd suggest you get something that will last a while, and not a 250, like a lot of new riders do. 250s are fun, but you'll outgrow them. Some folks say the same thing about 500s, like the Buell Blasts, which are inexpensive yet made by Harley.
You can pick up a vintage bike, see if riding is your cup of tea, then spend the big bucks on a new bike. Some folks discover they don't like riding after they get on a bike.
Good luck, and ride safe.