Boston – NY – Philadelphia- Washington- Pittsburgh – Buffalo – Albany or vice versa. Has anyone done something similar before using those cycle trails that are on the map to tour that circle?

It’s hard to understand your question – are you looking for feedback on the individual legs, or the idea of riding it all as a loop? And at this level of map detail it’s difficult to tell exactly what routes you’re thinking for each leg.

Your north/south from Canada-NYC and east/west from Albany-Buffalo are both the Empire State Trail, the east/west basically being the Erie Canalway. Those routes are very well-documented and there is r/eriecanaltrail as well.

Portland-Boston would be a patchwork of rail trails, mixed-use paths and small roads. South of Portsmouth NH many of the segregated paths to and through Boston will be only a few miles long and the routing will get a bit complex and chaotic – I live in that area, it’s a network of connectors between small cities. I’d probably choose to cut east/west across MA to pick up the Empire State Trail and ride through the Hudson Valley instead.