It's funny that you mention Settlers, since every time I've played it's always been quite obvious after the initial pieces are laid who will win hours later. If you don't have the good spots, it's a painful, slow grind to defeat.
However, it is a hugely popular game, and I'd love to know why.
I suspect that you're playing it wrong, or with the wrong people -- particularly if it's taking you hours to play.
Typically, there'll only be one or two really good spots (say, 8-10-5 or something). The players on those spots will/should get a disproportionate share of the baron, both because they have more cards and because they're in the lead and need to be dragged down to everyone else's level.
The game then becomes an issue of trying to get good without appearing so and picking the right time to make your move, rather than 'I have x points/regions, therefore I win'.
Sounds pretty similar to the Monopoly rules, now that I think about it...
I think it's popular because it is mostly random chance with a veneer of strategy. It's a clever game in that it equalizes people who think about it a little with people who think about it alot, but gives both those groups an edge of people who don't think about it at all. This makes it more accessible to people who wouldn't otherwise consider themselves serious gamers because if you try, eventually you'll get lucky and win.
However, it is a hugely popular game, and I'd love to know why.