biased about her hometown

Understandable, even if I have no particular fondness for any place I've lived (including Kansas City, Denver, and Phoenix). I can tell you some things to do in the cities (e.g. Denver museums), I wouldn't necessarily rate them as top-notch. There are much better (and more extensive) displays of armor -for example- in Windsor Castle. Phoenix does have the largest -last I new- museum about Native Americans (The Heard Museum).

In Denver, I'd honestly recommend driving to Boulder, or Rocky Mountain National Park. More scenic than the city. The city itself never impressed me, and I lived there for four years. There are museums, but there are better elsewhere.

For Boston, I know American history, and I know -this is gonna sound weird- what I learned playing Fallout 4. Lexington/Concord, Bunker Hill, Faneuil Hall, the Golden Grasshopper, Boston Library, Old North Church, the "Freedom Trail", and -if the game is accurate- a fortress (Fort Independence?) featured in the game. We're not "pubbers", so unless there is something really good there (like in England..."pub food"), we wouldn't go.

We're boarding a cruise from there. We often (not always) plan to arrive earlier in case of flight delays and such. The question is "how much earlier". We could walk the Freedom Trail (2.5 miles...I looked it up). I would like to see the USS Constitution, though 1poorlady likely would be less interested in that. She would humor me, though. She would want to try some Bostonian food specialty (me too!), if there is one. That would only warrant an overnight, though. American food doesn't get us too excited because we eat that all the time. Food courts in Iceland or Thailand, for example, feature stuff we have never seen, and we'll nibble lots of stuff. Though the lobster roll is Maine was really good.

A bit of rambling, here. Hopefully I conveyed some of what we look for. Less museums, more sites/sights, and more unique foods.