Better to figure out what you want to ride, and where you want to ride it first. That's another of the reasons to get a small (inexpensive) bike first. There aren't many people who enjoy riding along long straight superslab as far as the eye can see, and in fact my ten pound cat could do that; the bike doesn't really need a rider at that point, just a throttle lock. For myself, the idea is to turn a 5 minute ride into a 15 minute one, a 5 hour ride, into 8, and be able to take stuff and a passenger for the trip. For others, it's to show off all the work they've put into their bike, others their mad skillz. Still others like to go really off the beaten path. With a small bike, you can do many of these things, so the idea is to A) learn to ride B) find your niche. There are other threads here that will tell you what happens when someone starts on a bike too big, and there are people who started big, and still don't realize what they're missing.