I'm thinking about running an adventure path at work, and I don't really want to run Scales of War or the ENWorld adventure path for various reasons, so Paizo's an obvious place to look. What are the pros and cons of the Paizo adventure paths with an eye towards 4e conversion?
My take on it is this: adventure paths that focus a lot on encounters that make more sense with small numbers of opponents (for example, the Skinsaw Murders, part two of the Rise of the Runelords) or confined encounter spaces are harder to convert: the aesthetic in 4e is to have larger numbers in the opposition with a wider movement space.
Also, Paizo has a taste for including eccentrically detailed opponents in their bosses or tough lieutenants. 4e's aesthetic, again, seems to lean a bit away from opponents with a big bag of tricks, and towards clouds of opponents that can do interesting things in concert with one another.
My advice on this here would be: don't try to hew too closely to the source material when you do a "conversion". Read as much ahead of the entire AP as you can, and then re-build the encounters with an eye to "what am I trying to accomplish here" rather than a strict numbers-to-numbers conversion: you want to translate, not transliterate.
I ran the first part of RotRL with 4e, and it worked reasonably well, once I figured out that I had to slightly redraw the encounters and the plotting to account for larger numbers of opponents in the encounters.
At the moment I'm running Second Darkness with 4e, and it has been successful so far.
I would say that any of the APs to date would be suitable for conversion to 4e: I would think that the urban ones, Council of Thieves and (first part of) Curse of the Crimson Throne, would require a bit more thought to convert. I suspect that Rise of the Runelords, heavy on tactical encounters and light on roleplaying and puzzling, would be quite straightforward, and Kingmaker with its sandboxy approach, translating quite nicely into quests, would also be interesting to use.