This weekend and next, with the holiday concerts starting to pile up, there are some that will inevitably be overlooked. Magen Solomon’s San Francisco Choral Artists, having just received a favorable review in Fanfare for their recent With Strings Attached CD, should make anyone’s shortlist of choral concerts to attend. SFCA opens its season with an adventurous mix, ranging from Renaissance polyphony to contemporary music. This is yet another possibility for concertgoers who are trying to avoid the usual carols and standard seasonal rep.