After my inital time on a dual sport that was way too big, I bought a ninja 250 and loved it. It was pretty small and light, but was perfectly stable at highway speeds. I could ride that thing around all day going 90-110mph so don't let the small engine size put you off, plus they hold their resale value really well, so buy one, ride it for a while until you feel you've out grown it, then sell it for a downpayment on new bike. Being able to get your feet flat on the ground is very reassuring when you're learning, which is how I picked the 250 in the first place, but once you're comfortable with riding and moving a bike around, there's no problem only being able to touch with your toes/balls of your feet.