Well, the obvious thing to do here is the Hermit/Market Square combo (
http://dominionstrategy.com/2013/02/11/combo-of-the-day-30-hermitmarket-square/ ). I bet that would be dominant in 2p.
The second thing is how amazing Procession is here - there's good stuff at all price points, $2-$6.
Double-tactician seems unviable, with Festival and Steward as the only virtual coins but Market Square as a great source of real money and with Rabble and Nobles for reasonable draw.
Big money + X entirely unviable , at least a priori.
In 4-player, a lot depends on your opponents. If your opponents go for marauders and then start building up a conventional engine, then Hermit/Market Square will just win formulaically, I bet.
If your opponents pick up multiple hermits and market squares, then the combo won't work; on the other hand, that means that two piles will be empty really early, so you probably have to pull the trigger early and buy up like Estates or something? Man, I don't know anything about hermit/market square other than theorycraft, I don't know how well it works if you pull the trigger early, can you get enough Hermit Plays/buys to buy up 8 estates and end the game the second the Hermit/Market Square piles are gone?
The other thing to do is to go for a more standard engine, with Procession to turbocharge it. I think that would work - but again, if there's competition for engine components, then piles empty lightning-fast, and its a question of whose half-baked engine is more effective when unfinished...
Man, the 4p makes it hard. I know what I'd do in 2p, but I just don't have an intuition for what piles are going to be gone and how well these different strategies work when they don't have time to go to completion and have to fire while engine-building.