Torgau. The depth of the deployment makes this battle almost impossible to do in 28mm.
My experience of gigantic battles is quite limited but, the gigantic ones I’ve played in have tended to become a bit tedious. Big battles, with one or two thousand figures, have been great, but the truly huge ones (more than 2000 figures, biggest 3500+) have just become pointless, overcrowded, painfully slow slogging matches. I’m not sure why that is. All, with only one exception, have been 28mm affairs.
What, BTW, is your definition of gigantic?
My whoring and daubing: