The princes/male heroes are a rare bunch! The exception is Hercules, as he can be found frequently. Hercules can be found at MGM either near the entrance or maybe by the Big Hat. He often makes appearances with other characters in the middle of the day (between noonish and 2:30ish) on half-hour intrevals.
The others mentioned are much harder to find!! I have met John Smith by the Big Hat at MGM, but that was only one trip and I never seen since! Like Hercules, he was there around the middle of the day (noonish to 2:30) on half-hour intrevals.

If he was around nowadays, he may be near the entrance like Hercules.
Prince Phillip does make rare appearances. He was at the Halloween parties, (except for the nights I was there!) so I never seen him. I think he does do meets during normal park days, but not sure how often or where.

And Prince Eric I think make sporatic appearances with Ariel in her Grotto, though I have no idea if he still does it or if he has recently.
Well, of your list, only Hercules may be an easy one to find! Happy Character hunting!
