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I'm a large amount of biker myself, so I understand your situation. If you consider the position of riding for a long time in a stretch, you'll probably be more comfortable on a bike that lets you sit more upright. Most "sport bikes" are the type that put you into a lean forward position with more pressure on the boys, too. So you would more likely be happy on a cruiser. There are many out there in the 900-1600 cc range that are several years old, not Harleys, that aren't so expensive. One like that would serve the purpose. The exact brand isn't so important if it's from a manufacturer that has dealers in your area. Not that you have to buy from a dealer, although that's not a bad idea.
In several years you could move to something more desireable, but you won't know for sure what you will want until you've ridden for awhile. It's possible that with the experience in a beginner's riding course, you may have enough skill to get by on a first bike larger than those provided in the courses. Then time in some parking lots will give you enough confidence to get out on the back roads. Then will come traffic, then freeways. Don't start out on a road trip.
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