I always have some form of taper to my leaders. But I do piece my own together. Saltwater for example, I will use 33 lbs Rio Hard Mono, 22 Lbs Rio HArd mono, to Orvis 20 LBS, Flouro http://www.thelowerforty.com/rx/rx011400.htm
This is from my local fly shop. This simple leader has really helped me lauch some big flies and turn them over easy. The Hard mono, is stiff, but it's stretch has helped absorb my mistakes when fighting fish.
For dry flies, I just by the tapered leader and continue to use the appropriate tippet to keep the leader well tapered for all nymphs and dries. I just find my presentations to be more delicate, and the drag on my nymphs to be less (I could be imagining that last part but it just feels better for me)
If I am doing some bass bugging and streamers, I will usually use some form of 10lbs Hard Mono and still tie of the matching diameter flourocarbon.
Alive without breath,
As cold as death;
Never thirsty, ever drinking,
All in mail never clinking.
- Riddle