Arriving in the morning is difficult on AA if not impossible as most, if not all, Europe to US flights depart mid to late morning from Europe, arriving mid afternoon to early evening in the US. UA has one flight to EWR that arrives at 10:30 a.m. That's probably the earliest you will get and is on UA, not AA. Do you need to fly AA?

For a longer layover, try a multi-city search.