Well, when I am in France I buy bottles of fizzy apple and other juice packed in bottles like champagne bottles, and much the same colour. It has all the pzazz of opening a bottle of champagne etc and it tastes delicious.
I buy these ostensibly for the GC, to drink when celebrating, but more often than not DD and I share the non-alcoholic bottle with the children, rather than the alcoholic fizz with the 'adults'. You do not need to consume alcohol to get a sense of occasion, it is all the stuff around the contents of the bottle that causes that, not the contents themselves.
The alternatives are not just glasses of fruit juice or colas