It now seems obvious to me that in the use of the word “sabbatwn" Paul is referring to the ceremonial sabbaths and thus that the meaning of the sequence given in vs. 16 has no specific relation to a yearly, monthly, weekly time progression, as previously noted, itis more likely a yearly-monthly-yearly chiasm..  The relationship between the terms chosen by Paul indicates that he is using a time-honored way of referring to the ceremonial days of worship of the “Jewish” religious economy

     Note the following attempt to paraphrase these two verses by Fields [pages 191-2]:

16 Therefore (because Christ is triumphant) let no one judge (and condemn) you concerning (religious laws about) food and drink, or in regard to a feast day, or (the feast of the) new moon, or a sabbath day (a day of rest).
17 (Let no one judge you about your observance or non-observance of these Jewish rituals,) which are (only) a shadow of things that are coming, but the (solid) body (that casts the shadow before it appeared itself) is Christ's. (He is the fulfillment of all these Old Testament ceremonies.)

     Of course, given the things that we have found above we can readily see how inadequate this paraphrase is.  But, it does point us in the right direction in terms of the types and kinds information that we are not given and thus have to supply in order to understand what Paul meant when he wrote these words.  So, if we were to re-write the verses and "fill in the blanks" with information we are not given we would have the following:

Therefore let no man condemn you (as the ascetics are doing)
  in (regards to your) eating and in drinking,
    either in regards to (the way, or how you celebrate)
  a feast day, or a new moon, or the Sabbath day:
    Which are a shadow of things to come;
but the body of Christ (that is, let the church decide these matters).

     Or, to more loosely paraphrase it:

In regards to your feasting or fasting, as the case may be, on the festivals, new moons, and ceremonial sabbaths don’t let the ascetic guide you in these things rather let the church teach you about how these are shadows of things to come.

     I am thinking that it is possible that Paul is getting a double-use of out of vs 17.  On the one hand, he removes the ascetics from judging what is right and proper worship.  On the other hand, he is saying that these things on which the ascetics judge are the shadow that point to Christ and without Him as their focus they lose their meaning and value (see Richardson).  If Paul had solely meant the latter wouldn’t he have used the word “is” (estin) to avoid any possible confusion?  It seems to me that what Paul is doing in this verse is to condemn "empty works apart from Christ" whether they be "empty Jewish symbols, ascetism for mystical reasons, [or] the national exclusivism of the Jews and their legalism of the Sabbath" (Coltheart [page 23]).  Likewise, Weiss feels that the believers “at Colossae [were] allowing the memory of sin to produce in them a feeling of incompleteness which [was] driving them to a system of dogmata in order to attain to perfection.”  He then cites Kasemann: “Where the forgiveness of sins is vouchsafed once and for all with eschatological finality, there cultus is to be found no longer.”

     Coltheart [page 25] closes his study with these words which I think is very appropriate here as well:

The real point of the passage is the opening phrase of verse 16: "let no man judge you ..." The liberty of the Christian from legalism gives him the fullest and deepest experience of watchful holiness and he is away from the judgment of his fellow-men as well as the judgement and condemnation of the broken law. To assert the pre-eminence of Christ is to resist the message of salvation by works and to cling to Christ's salvation.

     We also need to consider the meaning and relevance of the seventh-day Sabbath to us today. For as one reader of this study has observed (paraphrased a bit): "The Sabbath is a sign, a symbol, of Jesus' creation and redemption. Although it can provide rest for the weary of any religion it is ultimately worthless apart from the reality, which is Christ."

Weiss, Herold “The Law in the Epistle to the Colossians,” Catholic Biblical Quarterly 34 (1972): 312.