…I don’t want to give bad advice. The one thing I know for a fact about the former Virago 250 (now called the V-Star 250) is that, due to its very light weight and relatively low power output, it may not be ideal for highway riding. The downside of going with a larger bike is that they are generally less easily maneuvered, and harder to control for newer riders. If you’ve had fairly extensive experience on the 250 during your lessons, you may be up to the task.
I would probably point you towards the Vulcan 500 or S40 myself. I have heard very good things from Vulcan owners, though I haven’t heard anything bad about the S40 either. A bit more weight and more power will make for a much more pleasant ride on the highway, but neither bike is large enough or powerful enough to present too much of a problem to a new rider. Just be extra cautious for the first few months, and really practice the crap out of your new bike (e.g. clutch control, emergency stops, tight maneuvers, swerves, etc).
One more thing: how tall are you? I’ve heard of tall riders having issues on the 250. I sure did when I took my MSF course. I would definitely suggest going to a dealer and sitting on all of these bikes. Comfort is a large part of the equation.