This is a bit off-topic, but I have the exact same most common use case, and I just switched in the last few days to using the Readability add-on to Chrome, which has a "send to Kindle" button. I was previously using Wordcycler to sync my Kindle with Instapaper by plugging it into my laptop, but this allows me to skip that step. Now I can just hit the sync button on the Kindle directly and it downloads the saved articles.
Readability seems to render articles slightly better, too, and more often keeps the byline, which was the most annoying part about Instapaper for me.