I've been riding for 35 years, and every ride is like nothing you'll ever experience in a car. The first bike is a more critical choice than most understand, particularly when it's a conscious decision to become a motorcyclist instead of, "I started riding because I couldn't afford anything else."
First thing you do is attend an
MSF Basic RiderCourse. Let that be the place to accomplish a number of things, such as set some good habits right off, provide a rider test waiver in many states for licensing, entitle you to a significant discount on insurance, and most importantly, help you discover whether or not you really want to ride. They'll have you on 250cc or thereabout bikes in a controlled environment. Loads of fun, really, and they're used to folks that haven't been on anything but a bicycle, and then not for thirty or forty years. Talk to the instructors about your riding needs, they'll also help guide you to a sane choice.
As far as a first bike, no need to spend over $5K, which will get you a nice new bike up to about the 500cc range, or a recent model up to 750cc or so. Plan on keeping it and learning about practical riding and your skills for about a year, and
then move up to something you want to spend more money on. Cruisers & Standards are generally easier & more forgiving, sportbikes are typically a bad choice for a first-time rider. As tempting as it may be, a new H-D or Victory for the first bike is a perfect recipe for disappointment. Start smaller, easier, and something that you won't cry over when you drop it in the driveway or at a stoplight the first few times.