While I've been talking about celebrating the Octave of the Feast of the Assumption (informally of course since it is no longer in the calendar), I came across another way of prolonging our remembrance of the doctrine through the feast, namely having a triduum leading up to it, as practiced by the Sons of the Holy Redeemer (formerly the Transalpine Redemptorists). They started last Wednesday with this magnificent catafalque in their chapel, so that they could gather around it in imitation of the Apostles.
The Catholic Encyclopedia lists quite a few sets of three days of prayer. The most obvious is Holy Week of course - but there are also (traditionally at least) the Rogation Days; three days of litanies prior to the feast of the Ascension, and Pentecost (both of which also had octaves in the older calendar); in honour of the Holy Trinity (which can be done any time), of the Holy Eucharist (around Corpus Christi), and for St. Joseph.
The Encyclopedia states that:
"The exercises of these triduums are mainly meditations or instructions disposing the hearers to a devout reception of the sacraments of penance and of Holy Communion and to betterment of life."
Hmmm, my calendar restoration campaign may be expanding in scope...