UniversalWolf: No, I don't mean I'm hunting my wife. That would be unethical. :)
What qualities should I be looking for in a potential wife? They apparently have different stats, dowries, and social connections, but I'm not sure how to tell a good choice from a bad choice, except for which city they come from.
A wife can give you a small permanent reputation boost in your hometown; there are three levels to this and it never changes over time, "knows nobody in town", "in contact with a few" "well established with the councilmen"... wildly paraphrased. I have no idea if the effect is noticable in a small game, I'd call it negligible. The kids you start getting every year supposedly add to your reputation as well. You can tell the "reputation rank" of future wives by their image
http://www.rjosephs.de/tools/heirat/heirat1.html lists them, mediocre on top, unknowns in the middle, bottom row the social butterflies.
Dowry is always at least one ship, can be several later. Your choice if you want to marry early or wait, one snaikka if you only have ten ships makes a lot more difference than three cogs when you already have a hundred. Some goods as well, but thats quite random, 50 salt aren't as exciting as 50 furs, but you won't know until the wedding day what you get.
The wedding itself counts as a party in town, like the ones you can hold when clicking on the market stalls. Can be a sizable reputation increase, but its temporary. Might even lose some rep if you really butcher it, but that passes soon as well. The sucess depends on your stock of various foodstuffs, if they run out of things to eat the letter next day complains. Hard to give numbers how much you need, it depends on the size of town, your reputation and maybe your wealth. If you don't care for the party boost ignore it, you still get wife and dowry if you don't prepare anything for the wedding. They really eat your wares, can make the whole thing a lot more expensive than planned if you try to be a good host.
One thing I avoid if I marry late is girls from river towns, not easy getting a cog out of cologne, as the dowry appears in the bride's hometown.
Reputation is the only thing about a bride that you really know before the wedding, taking one of the first offers gives you a snaikka, as lord mayor you can expect 3 ships, cogs and crayers. All those ships can be in a really bad state.
Marriage is a very, very small part of your bussiness with lots of unknowns that you might influence a little with savescumming if you'd like. Whatever you make of the dowry ship probably has the largest effect. You won't harm your game if you pick someone whose pic you like even if they don't know anybody.
