You can actually check out crime stat's on trulia.
Example, south boston:
There are some really nice parks on the "eastside" of south boston which is also near the water (pretty park called Marine Park with a path that runs along the ocean).
The "Seaport District" area in South Boston doesn't really have formal parks although they are putting in a board walk-type park along the 4 point channel which should be nice.
If you look on a google maps you can actually see where the parks are in south boston (marked in green along with names) ... check out this one:
The West End is much smaller and is more large condo developments so not sure about local "parks" per se, however, it isn't a far walk from The Commons (the walk is through beacon hill essentially) a beautiful and well-maintained park.
Both areas are pretty different and are also in totally separate parts of Boston.