I was wondering the best way to get to all not by driving. Is there a bus tour or something we can use. It will be 3 adults and we would be in Niagara falls for 3 days.

I know of no bus tour or mode of transportation that include such diverse destinations. Three days in Niagara Falls is at least 1 day too many, if not two.

Second the comment about Niagra Falls, and wonder why Hershey is so high on a list.
And no, there isn't a tour for that. Rent a car.

https://www.rome2rio.com/s/Niagara-F...ey-Park/Dennis

I would look at the falls, get back in the car and head to Cape Cod via Boston.

You could certainly use Niagara Falls (either NY or Ontario) as a base for many excursions--Niagara on the Lake and the Shaw festival and nearby wineries, the Welland Canal and the locks, Buffalo and its arts, architecture, and history.

I would combine Niagra Falls with Buffalo, N.Y. which has a lot to offer. But 3 days would be a good amount of time for both. They are only a short drive away from each other.

I am just curious why Hershey, PA? It has a children's amusement park, some chocolate shops, museums, and an interesting history but again I would just spend a day there and it seems out of your way? Are you visiting friends or family?

Today's Sunday NY Times has a glossy inert promoting the Niagara area. Could be just the NY Metro edition.

Where and when will this trip start? You can ride an Amtrak train from eastern New York including NYC to Niagara Falls (NY or Ontario). If you visit Cape Cod first, you can take the Boston branch of the Lake Shore Limited to Buffalo arriving about midnight. Rent a car or take a tour from somewhere in Buffalo.
IMO there are better amusement parks in PA than Hershey.
The candy bars are no longer made there - pity.