How long do you think the rights should last? Do you think the Poles in the postwar period with their talk of 'recovered territories' and the 'repatriation' of the German 'settlers' were correct?

Only a tiny minority of Germans would actually return to the birthplace of their great-parents. That said the Chech laws after 1945 didn´t distinguish between supporters of Hitler and people resisting him. So the laws might be a touch insensitive...
The number actively involved (as opposed to passively supporting) was a small minority of the population. In any case depending on how the question was asked a clear majority of the expellees wished to return into the sixties. A right of return was the official policy of the German government until Brandt, and remained the official policy of the expellee movement long after that. And if the expellees had been kept in refugee camps as second class citizens (Jordan, occuppied territories) or non-citizens (everywhere else) I suspect that plenty would still want to 'return.' Conversely, if the Arab governments had had a deliberate policy of scattering the refugees throughout the rest of the population, breaking up old local communities geographically, and providing financial aid and partial compensation for lost property I imagine we wouldn't be all that worried about the Palestinian refugee problem today. (To be exact the Bundesregierung had a dual, contradictory policy for the expellees. On the one hand the practical one described above. On the other a propaganda/cultural one seeking to preserve their local identities so that they would want to return - hence the large scale funding of the Landsmannschaft movement and its associated organizations.)

Re. the Baltics - you do realize that Vilnius had a Lithuanian population of at most 5% in 1939, and no I don't think the Poles (or rather their children and grandchildren) expelled from Lithuania, Belarus, and Ukraine have any rights with respect to those countries.

And as a final note, a poem by the Polish poet Anna Frajlich, about her home town of Szczecin, formerly Stettin. (translation mine)
City

A sharp western light
strikes my eyes
a different view greeted me
from my childhood windows
from one side gardens
stretching out in the distance
from the other end of a street
planted so thickly with lindens
that their crowns formed a tent
the light as in a tunnel
somewhere in the distance
round and promising
the city was not ours
but taken from others
who fled here in the wartime
chaos and left everything
either buried in the gardens
or covered by the rubble
or simply on the table
red wine in crystal glasses
unfinished
dark stains on the sides
the city was not ours
but it flowered for us
berries and apple trees
in countless gardens
violets and lilies
in the hedges' shadows
flowered
the city by the river
spilled out along the borders
and in this city one heard
various languages
--like the bushes -- transplanted
from east to west
someone drawled in from Wilno
someone's Lwow gentry maners
-- in a whisper someone still spoke in German
and the survivors' Yiddish
filled the streets
and on the riverbanks
the city slang
already grew like grass
among the stones
and it is such an image
that endures in my mind
sometimes somber and then again
full of summer glare
spring autumn in the smoke
of burning branches
the city of my childhood

taken from someone
so that someone else's childhood
would pass by elsewhere