No reason to equivocate. IMHO: hook your dad up with his vision or riding cruisers with his son. Truth is that for many of us motorcycle is 90% of it, sport vs cruiser vs dually is the rest. If you eliminated two of the three above classes, I’d still find something to love riding. And I’d thank God every day I got to ride it rather than being jammed into my incrediblywell-equipped and luxurious car.
I would seriously advise you to try out a bunch of bikes, including use bikes. If you could find your way towards a slightly used bike, the Honda Magna is an awesome compromise between cruiser and sport bike. It’s often classed as a sport-cruiser, but is probably the only one in the 800 range. It’s a giant-killer and it’s power demands respect . It’s also wickedly cool looking.