Originally Posted by amislove

Picking some random flights from the Google link above, I can price it at $4.8k:

1 UA 30 Z 12JUN S EWR MUC 0540P 0735A 777 0 /E
2 LH 2476 Z 16JUN Q MUC LHR 0245P 0345P 32N 0 /E
3 LH 905 Z 20JUN M LHR FRA 1130A 0205P 32N 0 /E
4 UA 961 Z 23JUN Q FRA EWR 1120A 0150P 77W 0 /E
1ADT 4845.87 4845.87

This is pricing using fare rule ZNW57ERC (EWR-LON, allowing 1 stopover each way for free), which has the routing rules at the bottom of this post. In brief, I see a way the fare will allow you to connect in ORD, but IAH and SFO are disallowed as connection points. Thus, I can price something like:

1 UA 323 Z 12JUN S EWR ORD 012
3P 0255P 739 0 /E
1 UA 953 Z 12JUN S ORD MUC 0610P 0945A 789 0 /E
2 LH 2476 Z 16JUN Q MUC LHR 0245P 0345P 32N 0 /E
3 LH 905 Z 20JUN M LHR FRA 1130A 0205P 32N 0 /E
4 UA 961 Z 23JUN Q FRA EWR 1120A 0150P 77W 0 /E
1ADT 4850.37 4850.37

But if you try to route via IAH, this fare doesn't appear to combine with normal one-way domestic fares, so you end up having to buy up to full J to pull it off.