Matt,
I ride a Honda VTX1300. Everywhere I go people think its a Harley because its a big cruiser. A place to start would be to take the Team Oregon Beginners riding class. They are offered at many of the community colleges. When you pass it also gives you a pass on taking the skills test at your local DMV. I would start with something of moderate size, say a 750 or so and a used one at that. That way, when you drop it in a parking lot, your driveway or God forbid on the street, you wont be dropping a 20K motorcycle. If you talk to anybody who has ridden for a while they will tell you that if you ride, and haven't gone down on your bike, its a matter of when not if. Not trying to scare any one off, just telling it like it is. Its better to get comfortable on a smaller, more maneuverable bike than a big heavy one. Riding on the street is a completely different world that dirt riding. I grew up on dirt bikes and never felt like everyone was trying to kill be till I rode on the street for a while.
Personally I love to ride. If its for you you will know it within the first few months, if not you will figure it out just as fast. Another reason to start with something less expensive than a Harley. On the other hand, like reefkeeping, people jumping into motorcycles and figuring out its just not for them is a great way for the rest of us to get some great deals on almost new bikes.