I just built a bike using bar-end shifters and Tektro Campy-style brake levers, and I am pretty happy with it. Although I probably would have used downtube shifters if my frame had the bosses for them.
The setup feels much more solid than Sora, which always seemed flimsy to me. Plus, I was able to hide the shift cables under the handlebar tape, which is much nicer than the exposed shift cables on an STI system.
Also, the non-indexed front shifting is so much nicer than fiddling with the index and trim settings with STI shifters.
If you plan to race, or feel like wasting money, go STI. Otherwise, bar-ends are fine for what you want to do. I think you will be happy with them, and they will last much longer than Sora levers.