For my flights - Do I call up the individual airlines after booking? Doesn't seem like you can choose a seat on CheapAir or Orbitz.

You didn't identify the airline/destination (domestic or international?), so it's not possible to steer you in a precise direction, but ...

If you have your confirmation/reservation code (usually a six letter/number configuration), you should be able to go to the airline website to verify your reservation. Once there, depending upon the airline, you should be able to choose/change your seats.

Be aware that some airlines make you wait until a certain date - for example, 90 days before your trip - to choose your seats.

Whenever I book through a third party like Cheap Air, I always confirm the flights on the airline's official website ASAP, just to be sure everything has gone through.

We rravel out of JFk to Venice on Delta (non stop), then come back with Air France (1 stop - to De Gaulle and then from there to JFK)

OK - Just realized that Orbitz DOES let you reserve seats and have done it

I will call the airlines to make sure that they have our reservation.

You can select/review seats on www.delta.com and www.airfrance.us.