Drive them, don’t hide them away. Take life's pleasures whenever you can.
As for a future investment, I don’t think they will be in the same category as early Falcon GTs, Monaros, Toranas, HDTs, are today. The automotive scene is going to change drastically in the next 20 > 25 years, either by obsolescence or legislation, whether we like it or not, and those who have put them away for a sunny day or profit are going to miss out.
When I bought my Monaro, my workmates all said “Why drive it to work ? Put it away in the garage and it will be worth a lot one day.”
My reply was that I bought it to drive it, and as for being worth a lot one day, not in my lifetime.
The only excuse I can think of them not being a daily drive, is if they are parked outside in the baking sun, getting covered with industrial fallout, leaves and bird-crap, or being driven 2km to the shops and back.