I am 5'-5" and 220 lbs. I have a long torso and short inseam (27"). It will be used for city riding with some exertion (city park trail, etc.), more than cruising and less than what I believe is referred to as "road". My particular measurements put me on the edge of the spectrum when it comes to choice. I have spent hours trying to find specs for a new bike but I am getting conflicting answers. I have seen size suggestions anywhere from 46 to 50 cm bikes (still not quite sure what that measurement means to the rider) and 16-17 inches. At this point I am not interested in spending an arm and a leg on a bike ($1,000+). I would appreciate any advice on size and bikes that I can consider. Thanks.

Probably what you want is called an urban/fitness bike. It'll be comfortable and pretty fast and easy to get on and off of. You're not too heavy or short to fit on a stock size; but you are asking for trouble going mail-order or used since you're not sure what you need. What dealers are in your area?

Something like this:

Hey spamis, the 46-50 cm size refers to the seat tube length:

First off, be sure you know your cycling inseam. You pants inseam is not the same things. Cycling inseam is measured by standing barefoot with feet about 8 - 10 inches apart. Then with a book, binder or similar object raise it into your crotch as much as you can. The height of the book from the floor is your cycling inseam.
But it would probably be best to go to your local shop and have them help you get the right size bike. Getting the wrong size bike would be a poor start of something that otherwise would be a lot of fun and provide a lot of fitness.

You might be looking for something with a longer effective top tube but a very slanted actual top tube. A coworker just showed up w/ a bike like that from REI. Your long torso can take advantage of the reach of a larger frame size (longer effective top tube) but your smaller inseam can get the benefit of a shorter seat tube. My coworker has the legs of a grasshopper so his version of this bike has the seat post jacked way the heck out. You could lower yours until the seat and pedals are just the right distance for your legs.

(note above I may have misread, maybe you don't have a notably long torso at all, but I think a slanted top tube bike is still what you'd be looking for).