I would recommend you go to the store and buy you a fish. I think you'll be much less frustrated in the long run. If your 1st floor walls have no insulation in them, since the 2nd floor walls are open, I guess it wouldn't be too difficult to tie a nut to the end of the string and drop it down from above.

i have a fish, and plan to use it to get the string through. but i know if i use a long enough string, i can pull wire up to the 2nd floor and have enough left in the basement to pull it back, attach another wire and pulle it up, etc.

i alread know HOW i want to do it, just not WHAT kind of string to use that wont break

Use a second fish.
No type of string is going to be as strong as a steel fish tape.
String is used to pull an occasional coms line, or even with air pressure to pull a fish or a heavy rope.
Even a fish gets jammed once in a while in a wall and has to be cut off and abandoned.

If the pull area is pretty clear you might be able to use string to pull the fish back down to the basement.
Regular poly line used for com cable pulls is as good as anything else.

I use a roll of waxed string that I got from my dad over 20 years ago. He used it while at AT&T fishing phone wires in houses. It won't break and doesn't fray and is slightly sippery around corners. The wax also adds a slight stiffness to it which is useful. Construction stringlines can work, but fray too easily and don't have any body like my waxed stuff does.

Get some fine sash chain - it works really well. It's heavy enough that it will fall all the way down to the basement, but it is also smooth and slippery and won't catch as you pull the wire up through the wall. I usually overlap the end of the wire with the end of the chain about 6 or 7 inches, and then cover the overlapping section with electrical tape. BTW - it has to be the fine stuff (sometimes it is also called plumbers chain)- regular sash chain WILL NOT work and will get caught in the wall. You might not find it at the big box stores - my Home Depot stopped carying it. I found some more at a local True Value.

Sorry - I neglected to say "dropping it through the wall" won't work so well if you do have insulation in the first floor walls. I'm so used to working on my house, which has no insulation, that I forget other people certainly have insulation in the walls. As you said, you might need to use a fish to get it down to the basement, but then I still think the fine sash chain would work well to pull it back up to where you need it.

Use polyproplene pulling twine. Why not pull all the cable together? That is the normal way to do it.

Here is a link that might be useful: http://www.allgearinc.com/AGPPPL.htm

On the buckets of pulling string........wow, it's sold in lots of 48 buckets and each has 6,500' !!! That's 312,000 feet. I don't care how large the contractor is, that sounds like a lifetime supply. AND they offer it in pallets of buckets! Wonder how many buckets that would be. There has to be some other use for this stuff other than just pulling.
I realize that it's probably not reused, but still, using up 312,000' is going to take some time.
Mark

I'm sure you can find the same stuff in smaller packages at some of the big box stores. That was the first link I found for stuff.

well, i may have lucked out, as i got the room gutted i found a few cavities that have almost no insulation most of the way down the first floor wall... should make fishing pretty easy and be able to pull the whole bunch up at the same time. good thing i still have the baks of old blown in insulation from other parts of the room i can stuff down there when im done!

Sash chain sounds like a good idea. I've used steel electric fence wire (probably about #18-20) for years. It's cheap at the farm stores (or at least used to be).

i ended up only using the fish... it seems that my "open stud cavity all the way to the basement" wasnt so open... there was a nice 6x6 at the bottom! but i just ended up using the fish to get it all the way up.