I like it because Cliff Walk is really stunning, I'm a sports fan (the Tennis Hall of Fame is there, as is one of the oldest baseball stadiums in the country where people like Satchel Paige played back in the day). Plus then you can also do the beach, a boat outing (we took a tour of the bay and visited the military base out there, it was a fun afternoon) and get a few decent meals.
It's a 2-3 day visit IMO and worth going, though in the summer it can get insanely pricy. One option in the summer is to stay in Providence, which is inexpensive that time of year, and just do a day or one overnight in Newport.
I know a lot of people focus on house and garden tours there but that sounds insanely dull to me. If you've seen one big, grand house and garden, you've kind of seen them all.