Batdog,
Let me pass on a couple things here. am a retired cop who spent over 12 years on motorcycle duty in some of the worst traffic you can imagine.
First you have the right idea. Go enroll in a MSF, or Motorcycle Safety Foundation coure and take both the basic and advanced rider courses. Once you have done that, THEN get serious about what bike you want to buy. You will have a much better idea of what kind of riding you want to do and what size bike you want to ride.
Remember most bikes are purpose designed.
The street bikes are good on pavement and not so hot on dirt. They are also mostly 4 cycle engines which is MUCH quieter than a 2 cycle job.
Trail bikes are set up to be lighter and taller. If you are not at least average height you will have trouble when you come to a stop as you legs might not be long enough. They are also "twitchier" in that they can maneuver quickly. The center of gravity is higher due to the higher road clearance and may be dificult to keep upright if you are not up to the skill level they demand.
The main choice as to type of bike will be determined by HOW you intend to use the bike. Urban or city riding is different from highway driving as is trail riding, but most bikes will be able to do them all to some extent.
I prefer to ride on pavement and have a street bike. A 90 BMW K75RT. I started on a Honda 350, then a Honda 500 four then went to BMW's. I have had 3 of them and have over 150,000 miles altogetner on that brand.
I trained on a MotoGuzzi then rode Kawasaki's (KZ1000P's) for the city. I went through 4 of them and still like the way they handled. They were set up very well for law enforcement style of riding. Heavy but much more nimble than you would believe and stable in town. I estimate I put in about 175,000 miles of intown driving on those bikes. There was very little distance traveling on those scooters. It was all in city traffic.
As I sad before, get those MSF courses under your belt and you will have a much better idea of what you want to do. The MSF courses I have seen done here have bikes available to ride so you don't have to learn on your own scooter. It will save you much wear and tear.
PS don't think you will be safe on side roads. Those are where people are LEAST likely to be paying attention. The collision that got me retired from the Police Department happened on a residential street at 30 MPH. I turned that Mustang into a banana with my Kawasaki wehn he hung a left tunr in front of me. Remember people are not usually looking to see motorcycles in traffic. They have a hard enough time just seeing cars, trucks and busses.
Mav