First of all, you should probably consider the facts. How is your son or daughter doing at the regular high school? Are they attending? Have they had enough time to really get connected? Have you as a parent made your best effort to get involved and find someone who is supportive at the school?
If you feel you have made all of the attempts to utilize the resources in the regular high school, then you might want to consider an alternative school. Visit the school and check it out before you make a decision. Many parents have misconceptions of what an alternative school is because we think of the schools that were called "alternative" from our days. Today's alternative schools are What will the alternative school have that is different?
Most will offer a smaller campus environment. Some young people (and old for that matter) really thrive in a smaller environment. Youth will not be able to "fall through the cracks" in a small environment. Staff at the alternative schools make an extra effort to get to know their students and to individualize their instruction. The other benefits of an alternative school include extra support for students with personal challenges. Some campuses have on-site sober support groups and counselors, some have child care facilities, many have the ability to adjust school schedules to fit the needs of students who are working full time or need to get caught up in credit.