alitalia is not a partner of bmi, so Im not sure I follow.
by the way; AA TLV-Europe is also around 20k one way.
with BMI, using any star alliance (CO, UA, LH, LX, US, OS, etc) its 40k miles, or part cash which is 20k + 135GBP, both obviously excluding taxes.
If flying directly to the states the taxes should stay withing reason.