As the first Pathfinder AP, Rise of the Runelords covers at lot of Varisian geography and history.
Curse of the Crimson Throne starts as a city adventure, but halfway through also moves into travelling mode.
Either of these is a good introduction to Varisia because they move around and visit many sites.
In my opinion though, Legacy of Fire has the best story arc.
My playgroup is moving toward the Pathfinder system. We've got the core books already and are wondering if anyone has a suggestion as to which Adventure Path(s) they would recommend to a group of veteran gamers exploring the Pathfinder world for the first time.
Council of Thieves is the current one and the first one expressly written for pathfinder rules.
It's urban-centric and it's got a lower end level than most of the other APs but that's not necessarily a bad thing. I think it's got a good mix of dungeon crawling and urban combat as well as plenty of opportunities for non-combat interaction. If that fits your desires I think it's a good place to start.
You could also wait a couple of more months and start out with Kingmaker which will end at a higher level (17th I think). It appears to be more of a traditional campaign setting where the heroes can actually rise up to rule a small nation at the end of the campaign. Pretty cool as long as it's executed well. It even promises to have some domain level rules incorporated so that your PCs can actually manage the nation.
Converting the older APs is also worthwhile. I'd suggest RoRL as it's a good introduction to Golarion in a standard campaign focus (village focus and dungeon focued).
In all honesty, wait until they are launching a new one (they come in 6 month runs) and get a subscription. You get a price break and free PDFs that way. The downside is, you don't know much about the later issues unless you wait for them to release before starting your game.
Here are my opinions of the already complete APs in your situation:
Rise of the Runelords: I'm running this, and it's a great classic fantasy gaming campaign, from goblins to giants to evil wizards. However, it is the first so it is a bit raw in places, and it can be expensive to find hardcopies since they are out of print. Also, it's 3.5, not pathfinder, which means updating. Not hard, but still. Looking back on it, I probably would not start with this one — I only did because I am a completist. The later issues are more polished.
Curse of the Crimson Throne AND Second Darkness: I haven't played either of these, but they are also 3.5 and would increase the GM paperwork by like 5%. That's really not much, but it's enough to put me off. By some accounts, Second Darkness is the least popular AP, but I take that with a grain of salt, because it has lots of drow. Mind you, they are Pathfinder drow, which are an improvement, but there's no accounting for taste.
Legacy of Fire: My personal favorite, this is a 3.5, plane-hopping, arabian-nights style genie-war with lots of gnolls. In my opinion, this is the best intro to some of the best features of Golarion: mainly the countries are pretty much self-contained genre-pockets, the histories are pulpy but well conceived, there's a nod to monster ecology (gnoll tribes, not goblins, in the desert), etc.
Council of Thieves: I don't own it, but it holds the distinction of being the only PRPG adventure path released thus far. If you want to avoid the paperwork of updating, but you don't want to wait for a subscription to release another full AP, this is your only choice.
UPCOMING: Kingmaker is set in an east-european analog with the premise of nation-building. I don't know much about this AP beyond the blurbs in the store, but it has been hinted that mass-combat rules will appear as a chapter in this AP. If you decide to subscribe (which I recommend since it is cheaper) I would start the subscription with Kingmaker Part 1.
UPCOMING: The Serpent's Skull looks awesome, but you'd have to wait a few months to get at it.
Hope this helps.