My initial thoughts where to cover the range of grapes, perhaps with a couple of bottles of one particular grape (the only thing fixed is the max budget). That way we can try one grape+multiple producers, or multiple grapes with one producer etc.
I guess you mean just the 'popular' varieties rather than literally everything, but even covering the main grapes would take months and you'd never do them justice.
I'd like to cover the grapes just to bring people into contact with the main grapes. We can elaborate around that with producers/years to show just how much something like a tescos value bottle verses a proper lightly oaked chardonnay can differ.
By all means cover the main grapes, but stick to one at a time. I'd say spend a month or two on both Chardonnay and Cabernet Sauvignon (or whatever red you choose, assuming you want to do both a red and white at once) and go through the entire range. You need to cover vintages (good ones and bad ones) countries, regions, production methods and producers in detail before you can move to another grape, or I fear you'll be spreading yourself too thin and not really giving people useful, real-world knowledge that they can use.
Riesling is another one that really differs - Dr Loosen 2004 is like a spritzer whereas Trimbach is bone dry in comparison.
Everything differs, it's
how and
why that would be useful to know. I'm sure you know the difference, but can you teach the rest of them?
I was thinking of a bottle of cheap.vs.mid range for each grape. We can make overtones against others as suggestions (although something that people can themselves outside the monthly budget).
Can't argue with that, but I'd say you need to get people into the habit of paying good money for good wine. All wine costs roughly the same to bottle, label and ship, so there's an entry point at which you start paying for the wine and aren't simply paying for transportation and bottling costs. I'd say you could select bottles from the £6 - £12 mark and really show off what each grape is capable of and teach people how to spot what they'll enjoy without having to resort to the generic producers.
Also remember that a lot of people will want to use this knowledge in restaurants and bars, and with the ridiculous mark-ups they add on it would be great if people could select based on knowing what they'll like rather than sticking to a price point and hoping for something good.
I know this is a bit busy compared to tasting a specific grape variety but I think we'd not get the uptake by doing this straight off. Once we find what people like we can dig deeper.
It's your little project here and I'll be happy to support you if you need any assistance, but I fear you'll lose peoples interest if you keep jumping around between the varieties.