Regardless of which editor you go with, the principals are the same. I would offer that vegas is easier to pick up for the beginner but premier does offer a bit more overall. I have taught premiere even when I did not like it and most picked it up easily.
As far as using with Sonar, since the rpograms do not interface directly, it will be a matter of processing audio in sonar and then exporting to wav format to be imported into premiere.