Is the dash an acceptable punctuation in this sentence?
Dances, parties, luncheons -- all these should be part of your senior year.
Yes it's okay to use a dash there. But strictly speaking it should be an em dash...
Dances, parties, luncheons — all these should be part of your senior year.
The shorter en dash is for value ranges, such as £100–150.
The even shorter plain old dash (aka hyphen) is for word-hyphenation.
EDIT: These distinctions don't really apply to casual/informal writing such as us here at ELU, but they are quite rigorously applied by professional typesetters.
Yes, I would say it was an effective use of the dash. As Larry Trask wrote:
The dash has only one use: a pair of dashes separates a strong interruption from the rest of the sentence . . . If the strong interruption comes at the end of the sentence, then of course only one dash is used.
In that sentence, colons are preferable.
Dances, parties, luncheons: all these should be part of your senior year.
Dashes are normally used in pairs to set off an explanatory remark, or an appositive. You use a single dash to signify a sudden change in thought, or before the citation of the author or source of a quotation.
We are going to—What's that burning smell?
Dashes are one of the least standardized of all punctuation marks. That said, the use of the dash in the example produces a perfectly understandable sentence. It serves the same purpose that colon does when a list appears at the end of a sentence.
Making things understandable is the purpose of punctuation. So the dash is fine.
P.S. Some may quibble with the spaces that separate the dash from the words. In some circles this is a no-no.