Should we be rewiring or pigtailing the aluminum wiring in our condo?
Aluminum wiring is not the fire hazard people would have you think it is.  In fact it is perfectly safe and there has been studies showing that the only increased chance of fire is produced with an improper installation.  This usually means that contractors using outlets or devices that are not rated for aluminum.  This does cause the wire to eventually overheat at contact and expand/contract so many times that it becomes brittle and can short.

Pigtailing aluminum is perfectly acceptable.  Your electrician would just go to every outlet and pigtail the aluminum with a short copper strand using a Al/Cu Wire Connector (these are usually purple for identification).  This is probably the best solution for lights and other "non" outlets.  For outlets you can pigtail or just connect an Al/Cu rated outlet.  

However your local building code may have stipulations - mine is fine with correctly rated outlets.  I have read in other places that they require pigtails and I have read in other places (an electrician driven county) that they require a rewire.