With 600k UR points you can go to a lot of places if there is award availability. Thats enough for Hawaii, Australia, Asia etc in business class for the 3 of you. United would likely be the best UR choice in terms of award availability given the popular time frame involved. Sometimes I'll just create a list of places we want to go and go down the list and the first one with award availability is the one we go to.
For springbreak we're headed to Berlin and then Munich, driving to Salzburg and hitting the castles in southern Bavaria before taking a train to Lucerne. I'd lean towards a Europe trip right now given the airfare and exchange rate. Paris wouldn't be my first choice personally but its popular for obvious reasons with lots to do and plenty of iconic sites. 10 days leaves lots of time to hit other areas and Europe is generally pretty cheap to move around in once you're there with mass transit and LCCs like Easyjet and Airberlin to get you around. I've used the site below to figure out what cities I can easily string together by train during a trip. The directions are very helpful and accurate
http://www.seat61.com/international-trains/trains-from-Paris.htm
Personal favorites of ours in Europe were Ireland and Budapest, both of which are cheaper than Paris (Budapest can be significantly so depending on where you go. Glass of house red wine for $0.90. A pint for $1.05)