If the OP must fly into EWR, then the OP will have to choose whether AA loyalty is worth several hundred dollars of additional fare. But there may be a cheaper AA solution: Perhaps the OP could buy a cheap SAT-DFW-LGA and then once at DFW, standby for an earlier EWR flight.

This would require careful planning to schedule a long layover at DFW (but less than four hours, of course) during a time when at least one or two EWR flights are scheduled. And the OP has to be prepared to scramble from LGA to EWR in case the standby option fails.