[Danneq]

Yuin PK2 sound great and don't isolate much and can be found for around $60. I'd definitely use those if I was in your situation.
 
I'd recommend Yuin's G2/G2A clip-on earphones, but they seem to have become difficult to come by. I bought mine from a seller on Ebay about 2 years ago and back then they were easy to find. They sound very good and balanced and isolate sound even worse than earbuds do. Nowadays this seems to be the only place where you can buy them: http://www.aliexpress.com/store/product/Freeshipping-YUIN-G2-In-Ear-Earphone-Headphone-HiFi-Clip-on-Headphon/908705_494777316.html
A bad thing about clip-on earphones is that they leak sound, so you might disturb your co-workers.

 

[Derod68]

Never heard of these but I will look into them. Great reviews on Head-fi and within the budget (or how much wife will let me spend) Just don't know if I want that size like the koss clip ons since want to be more subtle and even portable. Great suggestion though! Thanks!!

 

[JackKontney]

Ah, so "Situation Awareness" just means "can hear ambience" more or less?

 

[Derod68]

Yes...'Sounds' (pun intended) like it. Leaning toward the Sennheiser PX100 II i. Watcha guys think? Under 70 bucks on Amazon.

 

[Danneq]

I haven't heard the PX100 II, but I own the PX100 and those are nice. I do prefer my AKG K420 to the PX100 since the AKG's are more fun to listen to, but the PX100 II seems to improve on the almost dark sounding PX100. If you intend to use them with an iPhone, I think that the deal on Amazon is good.
I seldom use my ultra portable headphones and clip-on's - I prefer to use either earbuds or bigger portable headphones (such as Audio Technica ES 10 or Sennheiser HD25) - but they can be very good for casual listening when you need to be aware of what's going on around you.

 

[Derod68]

You guys have convinced me to go with the earpads/portable headphones. I think it will def meet all criteria needed. Will still try the foamies! The senn px 100 II has some more bass, without all the isolation to hear if I am summoned. The ii version even has the mic to boot but primarily for work PC use with the occasional call during breaks and lunch .

 

[Iron-Buddha]

Not sure what source you are using, but you may want to consider an application like Awareness, that feeds in audio from your phone's microphone into the headphones once it passes a certain Db.  
 
Just saw you are using a desktop.  You could always plug in a microphone and control the mix via software.

 

[JackKontney]

For a mere $2000, you could get the Sensaphonics 3D Active Ambient, which has full-range binaural mics embedded in the earpieces and a Full Ambient mode that lets you hear the room at unity gain. Also gives uncanny natural directionality to ambient sound sources ("3D") and acts as an adjustable hi-resolution earplug when no source is plugged into it.
 
Maybe just a bit of overkill for your situation, but if you want true Situation Awareness...