When I started writing my current story I had no plot. In fact I had nothing. I just sat down one day and started writing in an effort to see what turned out. Now that I am returning to the story properly, I looked through the various plotlines trying to work out how to mesh them together. In the end some were set aside for use another day leaving just two main plotlines. It took some thinking and pondering of ideas to figure out a way to mesh them properly so they connected and told a single over-all story. It has breathed some fresh life into the story, now that I know where it is going and how it will end.
A trend of late in fantasy stories seem to be to churn out large volumes containing literally dozens of plotlines that seemingly have no connection to each other beyond being in the same setting. In the long run, ten books in, they may connect, but in the current book they may never meet.
If you look at Lord of the Rings, it had three main plotlines. The first was of course Frodo and Sam. Aragorn, Gimli and Legolas made the second and Merry and Pippin the third. There were other, lesser plotlines – such as Gandalf, Eowyn, Boromir and the like – but they wove in and out as needed. Those three main plotlines kept touching on each other even when they weren’t connected and in the end of the story they formed the whole story.
If you look at the late Robert Jordan and the current Stephen Erikson on the other hand, they stuff their novels with so many plotlines and characters that it is a struggle to keep track of them all – especially when a book can go by in which the plots followed never once met up or even mention each other. They are like two or three different books cut apart and then pasted together.
I think initially that was a way my current work was going – but I have since changed it. Yes, there are other stories of other people I wish to tell in that setting, but I won’t mash them all up together. Instead they will follow separately, hopefully, in their own work so that their stories aren’t lost amongst all the others.
Mist and Shadows 
I tend to agree with you on the tons of unconnected plotlines. Everyone raves about George RR Martin, but that was the very thing I found distracting about his otherwise good writing. Too many things going on that aren’t connected.
The idea that there is plenty of room form many stories in your world, but that they don’t have to be crammed together is I think a smart choice. It’s also one that I think will serve you well in the long run.
I’m playing with a story with three different plotlines (from three different historical periods) that still manage to interconnect. Which is great fun, but I’m hoping people will be able to follow along with the links between the storylines.
Looking forward to reading what you’ve got. (even though I’m so far behind in my reading)
I’ve read Martin, but like Jordan and Erikson haven’t read all the books out yet. As far as I am concerned there isn’t a reason to read them until the series is ended – otherwise it is so long between books you have to reread all the previous ones to remember what is going on, and even then it can still be hard.
Martin has the added problem of being so depressingly morbid. I have nothing against killing characters off – I generally prefer it if not all of them make it – but Martin goes way overboard.
Erikson is a bit different. Many of his books are fairly stand alone, but still suffer the mash up of multiple books within books problem. One example is Deadhouse Gates, one thousand pages long. There are four mostly unconnected stories going on in it. One of those, known as the Chain of Dogs, is quite brilliant and could just as easily been written as its own book. Instead it gets mixed up with other stories and loose some of its impact because of it.