Do you ever favor cefazolin over ceftriaxone for bacteremia with susceptible E. coli?   

No

We do cefazolin often unless h/o ESBL or complicated infection or procedural history. It is our preferred abx for pyelo or intra-abdominal infection (we add Flagyl for intra-abdominal) and is driven by our local susceptibility data.

No, I prefer 3rd generation Cephalosporins(or higher) for gram negatives.

Typically no.