My comeback from yesterday: after establishing a 4-0 Province lead on me, my opponent resigns with the score at 16-16.
I opened Ambassador/Silver/Ambassador against Ambassador/Ambassador/Silber, with my sights set on eventually having a City/Wharf/Ambassador deck that would draw itself while continually attacking, using any spare $4 buys on Caravans.
He went for a Minion deck, and bought Provinces as soon as he could, but without much money apart from 6 Minions which were also needed for cycling, his deck choked up right as mine was taking off.
Once my Wharves and Cities were established, I was able to easily shrug off the Minion attacks, and with the plentiful actions at my disposal I picked up a Curse and 2 more Ambassadors. In my last two turns I bought a Province and a City, then a Province and Duchy while successfully passing off all 10 Curses, at which point my opponent resigned.
It was very satisfying to see a really long-term strategy and have it come to fruition after being down 26 to -1 after 24 turns.