Elaine and I had a nice flight of Kopke Colheitas on New Years Eve at Wine Down in Portland, OR (http://www.winedownpdx.com/joomla/). We tasted 1957, 1967, 1977, 1987, and 1997. I did not have large portions of each and did not have paper, so each wine was not noted in detail, but I did note the progression of taste among years.
1997 was the lightest in color, a light burnt orange and had the most acidity making the wine slightly dry. The taste was with vibrant with dried fruits, and a bit a vanilla. Finish was moderately long.
1987 had a bit more depth in color then 1997. Slightly less tannic, the concentration was deeper but still crisp with a more nutty flavor. Finish was moderately long. Similar to a good 20 year tawny.
1977 was similar in color to 1987 but was more concentrated. The acidity was reduced compared to the 1997 and the finish was longer.
1967 was noticeably different from the three previous wines. The color was reddish orange and showed more depth. The nose was more concentrated and smelled of dried apricots, dates, and raisins. The plate was markedly different with deep concentrated apricots, dates, raisins, wood, peel, and a touch of vanilla. The finish was very long and fruity.
1957 was overall similar to 1967. However, the palate was a bit deeper and the fruit flavor was outstanding with notes of toffee. The flavor was complex and the fruit finish was long and memorable. The best tawny I have ever tasted - and my oldest for that matter.