I think Jetstar still hold the A330-200 record non-stop flight (TLS-MEL on an empty delivery sector in Feb 2011). 19h48m.
I've done 11:30 in an A330-300 (empty), but I've quite comfortably done LGW-CUN (10:00), GLA-SFB (09:00) and LGW-YVR (09:30) in it with a full pax load (233t MTOW). You are right to say cargo capacity does then become quite limited though.
MAN-LAS should be no issue.
I believe the longest regular scheduled routes by A330 aircraft are:
A330-200: Delta DTW-HND (12:10, 6,413nm)
A330-300: Turkish IST-ORD (12:10, 5,490nm)
Both are probably payload restricted I'm guessing.