Top of head figures for B737
Takeoff - 3000 kg/hr per engine
Cruise (at FL 3XX) 1100 kg/hr per engine.
For the 737 in particular, compared to the Tonka/Harrier, there really is a massive difference in fuel flows with aircraft weight, particularly for cruise. The above figures might be for typical TO weights for a '300.
Naturally OAT/altitude and amount of T-O thrust required play a huge role as well. If you're doing a PC simor something the above figures should be closeto what you need.