DB,

I would not consider choosing a flyline "the small stuff' since it is the line that is presenting the fly. But I will agree that you can pick from any of the companies out there and get a good product. The hardest choice is what taper. If you will not be doing a lot of distance casting 40' or over I'd choose a dt line. On normal to short casting the presentation is the same with either wf or dt lines so the dt saves you money by being reversable. The Dt is also easier to roll cast and on water mend.
I have to agree with FlyBinder that the Teton #6 might be too much reel for a 4wt rod the #4 would have been a better choice but you can lighten the initial drag on that reel it's in the directions that came with the reel.

Tom