Despite my wife, my friends, and I all having wildly divergent strategies, the mint rarely gets built. I agree with the other reply that there are just too many other things that are worth more to build. If you get unlucky and pull a gold resource for your first settlement expansion, it might be worth it, but even then I probably wouldn't bother.

I'll list my priorities for building, not that I'm all that great of a player. My wife seems to like to "chase windmills" more than me and she beats me all the time. I'd love to hear others opinions:

1. Settlements (plus roads, of course); but I'm actually content with just four, unlike most people I've played.
2. A garrison between the sheep and ore resource cards.
3. Scouts (to put identical resource cards next to one another) + resource doublers (mine, mill, etc.).
4. Knights (only the cheap ones); I actually worry more about the black number than the red number, as the "conflict" event really steams me.
5. Cities
6. Aqueduct
7. Enough windmills to get the merchant token, especially fleets + the harbor.
8. Anything that will give a victory point. The colossus (if played) should be the _coup de grace_ for fear of the arsonist.

I also make it a high priority to get yellow "action" cards, as they're free of charge to use. I personally think the spies are the flawed "game breaker" cards. The big piece of strategy that I haven't gotten a hang of is knowing when (and how often) to pay to "cherry pick" a deck That’s what I use my gold for, by the way). My memory is terrible, which is also a big problem. I still love the game though. Someone posted an excellent strategy guide a year or so ago. A dejanews search of "kartenspiel" might turn it up.

I would also love to know when the expansions will be printed in English, and I also agree it's a great game to get the wife to play, especially if you've already hooked her on the board game.