Yes, 60K is the most for a domestic rountrip ticket. What the OP should have done, and granted given the circumstances and getting his girlfriend home was the most important thing, this probably did not occur to him.

Should have booked the 30K high for the outbound and then found any low end award for the backend of the roundtrip for 12.5K so it would have cost 42.5K.

Something like SRQ-SLC for the high (30K) and then a return anytime that had low inventory would work. Also, on nwa.com you could even book multi city like SRQ-SLC outbound for 30K and then you could just type in something like ORD-DTW for the return which always has low inventory available and then book it for 42.5K. Even if you have no intention of using the second portion of the ticket, it would have saved some miles.