Thomas, I found this exchange on Purple very instructive.
Note how this grammatical point intrudes on an otherwise very interesting discussion, and how Jancis dances around to conclude that although superficially folks are discussing "varieties", in fact they are discussing wines and therefore "varietal" is correct.
Also note that "varietal" is an adjective being used a noun when discussing wines made from a particular grape. This is apparently [?] the grammatical sin that damns "varietal" when using "varietal" to describe a grape.
Finally, note that the original questioner wasn't sure which word he should use, so he used both "variety" and "varietal" in posing his question. And, Jancis answers initially with "variety" but concludes that "varietal" is really correct.
Which varietals are aromatic? publication date: Apr 21, 2006
Paul Tudor, Basket Press Ltd, Auckland:
Are you able to settle something for me please?
Which white varieties would you class as "aromatic" (as opposed to everything else which is presumably "non aromatic"). Alas, the Oxford Companion does not have the answer.
me:
Sounds as though you may be organising a tasting… Off the top of my head I’d nominate the following most obvious candidates:
Riesling
Gewurztraminer
Muscats of all sorts
I’d also describe Sauvignon Blanc as very aromatic but probably not a
variety [???] to be lumped in with the others. Is this enough?
Patricia, London:
If Paul is thinking like the ‘illustrious’ Institute [of Masters of Wine? – JR], then I would add Albariño/Alvarinho, Viognier and many of the German crosses (Huxel, Bacchus, Scheurebe, etc) as very aromatic, and Pinot Gris/Grigio, Chenin, Grüner and even Pinot Blanc as ‘semi-aromatic’. It is the likes of Chardonnay and Semillon (and most of Italy's indigenous varieties) that are the most neutral. Not sure if this helps or hinders.
me:
Interesting. I did consider Pinot Gris and then decided it wasn’t aromatic enough in many examples. Any funnily enough I don’t find today’s Albariño that aromatic myself – though when I first came across it I used to describe it as ‘peachy’. I certainly agree that Viognier is very aromatic. Am increasingly impressed by Laurent Miquel’s Viogniers in the Languedoc.
William Roach, Putnam Wine, Saratoga Springs, NY:
‘Which varietal is aromatic?’ is the question. Ought it to be: ‘which variety is aromatic?’ Does it matter?
As always. thank you.
me:
Ah! Well as you know, no-one is more conscious of the proper distinction between ‘variety’ for plant and grape and ‘varietal’ for wine made from a single grape than me. But I consciously decided that what we’re discussing here is wine rather than plants. OK? [OK with me, but a couple of posts earlier HRH used "variety"; ok, everyone slips from time to time, especially on this nice point of grammar.

]
Mark Davidson, International Sommelier Guild, Vancouver:
Thought I might throw Torrontés into the discussion about aromatic varieties. I poured one for a practice blind tasting for my Sommelier students a couple of weeks ago and aside from them all hating me for it, most thought it was some sort of Muscat. Not a bad guess given the possible Muscat connection in the parentage but definitely aromatic.
By the way the wine was the Crios de Susana Balbo 2005 Torrontés. Delicious and not too expensive.
***
While I'm in Jancis' world, here's her most current take on "varietal" from the OCW3:
varietal:
descriptive term for a wine named after the dominant grape variety from which it is made. The word is increasingly misused in place of vine variety. A varietal wine is distinct from a wine named after its own geographical provenance (as the great majority of European wines are), and a generic wine, one named after a supposed style, often haphazardly borrowed from European geography, such as ‛Chablis‚ and ‛Burgundy‚. Varietal wines are most closely associated with the new world, where they constitute the great majority of wines produced. The concept was nurtured by Maynard amerine at the University of California at davis in the wake of prohibition as a means of encouraging growers to plant worthy vine varieties. It was advocated with particular enthusiasm by Frank schoonmaker in the 1950s and 1960s, and was embraced during the california wine boom of the 1970s to distinguish the more ambitious wines, often made from Cabernet Sauvignon and, increasingly, Chardonnay, from the lack-lustre generics of old. Varietal labelling was also adopted, for a similar purpose, in australia, south africa, new zealand, and elsewhere.
Regards, Bob