then definitely book one way tickets. the only disadvantages may be with upgrading as you would have to use more instruments if you are planning on upgrading. also, if one of the one way itineraries ends close to the time that the other begins, you may have trouble as you might have to leave the secure area, pick up luggage, and re-check it. you also might have problems if they are close together and there are irrops as ua may not treat it as a misconnect, but instead as being late to your next flight.

plus, another disadvantage is that you are going ord-sfo in coach