Well, you are gonna have to set some time aside to go have some fun at dealerships! Only you can truly tell if any street bike is right for you. Things you want to check out-how does the bike seem to fit you? Is the reach to the handlebars comfortable, is the seat comfortable? How about the riding position-put your feet up on the pegs floorboards, now could you maintain that for hours at a time? Can you touch the ground with at least 1 foot? You will need to when stopping. Most bikes can be lowered at least 1" and the handlebars rotated backwards to ease the reach.
Engine size I don't worry so much about, because the bike has to fit you, before you will be comfortable on it. The engine could be a 1000cc but if the bike fits you, you can control it. The engine is only as fast as the throttle hand controlling it. Most beginners choose cruisers in the 500-750cc size. why low to the ground, narrow, and are quite capable of riding all day long hour after hour. A good used starter bike is the Honda/Yamaha/Suzuki/Kawasaki 400-450cc standard bikes from the 80's available fairly cheaply, plenty of parts still available and just wonderful lil reliable bikes.
