Walking around Boston, make sure your health & life insurance policies are updated...jk
Perhaps you & your wife may like Newbury Street
There's the Prudential Center - "The Pru"
[The Prudential Center is located near several mass transit stations including: Back Bay Station – commuters can walk from Back Bay Station to the Prudential Center without going outside! Prudential stop on the E line on the green line of the T. Hynes & Copley stops on the B,C, D lines on the green line of the T.]
You may enjoy the "Skywalk" - http://skywalkboston.com/
The famous North End - not like it used to be - but, for someone who has never been, you wouldn't know. The North End was nicknamed "Little Italy." A lot of Italians & Sicilians who came over settled there. Maybe you find a "long lost cousin?" jk.
My family settled there as well as other surrounding neighborhoods. Restaurants, little markets & bakeries were plentiful; inexpensive & delicious. Over the decades, it's changed a lot!!
I favor Spinelli's - but they're in East Boston & Lynnfield - not convenient w/o car.
The Boston Pops - not sure if they'll play that weekend. Maybe there are other concerts at the "Hatch Shell on the Esplanade" - people line up in the early hours with picnic coolers, blankets, chairs to secure a "lawn seat."
Visiting Labor Day Weekend, it'll be jam packed w/travelers, locals, festivities, college kids settling in, end of summer traffic.
Massachusetts Sales Tax is 6.25%.
A (metered) taxi - you can hail one - they'll practically screech up on the curb. I don't know the rates; I don't use cabs.
Crossing Boston streets - look 100 times in each direction....a car will come out of nowhere...Drivers don't always obey traffic signals, crosswalks or they try to pass a stopped bus.
No need for a money belt. As I tell people on the forum, just practice awareness & a big city awareness.
Trains & buses will be crowded. At train stations, make sure you stand "way back" from the yellow line...there have been instances where crazy people have pushed people. Just making you aware...You'll be competing with locals, travelers, musicians, & homeless people.
For train travel, there's the "Charlie Card" - https://en.m.wikipedia.org/wiki/CharlieCard
Past 8- or 9:00 PM, stay away from alleys (shortcuts), "The Boston Common" & "Downtown Crossing" near "The Financial District." Once businesses, banks, law firms & the like close, it becomes a little eerie.
Downtown Crossing shopping is nothing to see anymore. The "Jewelers' Building" was great in its heyday. The whole building housed many jewelers - eons go, when gold was dirt cheap/reasonable, you could bargain by comparing with competing businesses.
Back in the day, there was the famous Jordan Marsh - well known for its blueberry muffins - bakery shop was in store. As wee ones, we would get so excited when my family brought home a box. Can still smell the blueberries...
There was Filene's - (Both Jordan Marsh & Filene's were right across from each other & competitors. They also decorated their store windows at Christmas - magical. Filene's had a lovely restaurant.
Filene's also had "The Basement" as it was known back then. They would get surplus of "everything" & sell it at deep discounts. I got some beautiful Italian leather products - gloves, handbags, clothes - for almost nothing. Now it's a little super market (Summer St) similar to a small Coop.
Perhaps you may like to take a peek inside South Station which is right across from the Financial District.
https://www.south-station.net/ - A mini Termini.