I've heard that the walk from the Swan/Dolphin to MGM is about a 10 or 15 minute walk. I don't know the answer to the question about the Jr. Suite, but I'm looking forward to finding out.
my understanding that the Jr. Suite rooms do not come with a balcony. It is about a 10-15 walk to MGM. Not a bad walk but if a boat to MGM is right there and you have the time, enjoy the ride!!!