to Ben,
These are decent arguments if you assume Luke was written in century I. Do you have some arguments that do not depend on this dating?
About the dating of Acts, I made a case Acts could not have been written during the Gnostic era (120-?) (explaining why "Luke" would hide Paul's letters (but still know about them).), more so 120 to 200 AD, because Christian authors (Aristides, Justin, Irenaeus, even if he acknowledged Acts ) and texts then came up with Jesus' disciples, right after the resurrection, went all over the known world in order to make converts. Of course, that was the very ideal way to start Christianity everywhere, by people who actually knew Jesus in the flesh. But the propagation of Christianity outside Palestine is very different in Acts, despite the efforts of the author to show otherwise. And that would explain why, among other things, Acts and Paul were not popular then (see Tertullian).
All of that, with the evidence, is explained here:
http://historical-jesus.info/64.html
That might not be a direct answer to your question, but I am not going to think about arguments in my favor for the case of Acts written during the Gnostic era, when I am certain gLuke and Acts were written earlier.
Cordially, Bernard