If it's evening, you can go to the "Top of the Hub" restaurant at the top of the Prudential Center and get a great view of Boston. The restaurant is a little pricey though.
During the day, most people visit Faneuil Hall marketplace aka Quincy market for shopping, dining and some entertainment. There are also street performers in Harvard Square in Cambridge. Easy to get to via the 'T' aka MBTA subway. There's also the "duck boat" tour which you might enjoy riding in an amphibious vehicle going through downtown streets and then cruising through Boston Harbor.
Depending upon what time of day, I may be able to meet up with you for a drink or coffee.
I'm visiting Chicago june 6th and start travelling from there to Moline to visit the John Deere plant. I was invited by JD and the journey stops in Vancouver the 14th. When we arrive in your home town we have a day off, is there something we should see during the evening ? We've been to Sears tower when we where there before. Any thoughts ??? Perhaps a cup a coffee at starbucks for a quick meet ??? If we are allowed. I don't have a travelling plan from JD but it's hosted all the way...