Gaming at work

So at my new day job I've been thinking of running some manner of table top game as a way to meet people in the office while also hopefully spending some time with those people I do already know.  The question is what do I want to run.  I've got a good number of options, which is the problem really: too many options.  I want a game that has the following elements:

• Low barrier to entry.  Something people can pick up and play quick.
• Light rules overall with some focus on action.  Everything I run becomes sort of pulp action, so a game that's already there may be better.
• Some manner of group character or communal advancement, ala Song of Ice and Fire, Reign, etc.  I'm looking for something with more meat to it than the city creation system of Dresden Files.  
• Something mechanically interesting to me.  

My main contenders currently are:

• Shadows of Azathoth.  Fits all the above, but isn't written fully.  Also needs a lot of rework.
• Song of Ice and Fire in some other setting.  Maybe rejigger it for a post-apocalyptic setting.  Or I could use the Reign rules, they have less granularity in what the group character represents but a lot more you can do with it. This in some ways is the least mechanically interesting, but would mean the least design work (which is a good and bad thing). 
• GodWar, my Renaissance occult superheroes game, but it lacks the group character option.  I could try and design one in.  This, like Shadows of Azathoth, would require a lot of rework.  
• Some manner of Western Marches campaign using WFRP 3rd edition, which would require buying some additional dice and possibly the new rule books since they seem better organized.  It would also require the creation of some manner of group character mechanic since the group sheet mechanic is pretty minimal.  I was thinking of some system where the players can upgrade the town they are based out of over time.  This may have to be eliminated due to the easy to pick up option as its not easy in my experience.  Not that the system is hard, just really really different.

Last Knights of Camelot isn't on the list as THE Ian Lemke may be playing, and I don't think he'll go for the robots and I don't feel confident in doing an Arthruian genre game that he would enjoy since that's sort of his thing.  Americana needs way to much work to consider. Also willing to look at other options.