Quik,
My apologies for the terrible manners in delaying my response to your very thoughtful response. I truly appreciate your candor and encouragement. The latter of which really was taken to heart at a time when I was ripe to hear it as this process, particularly with the new MCAT changes, certainly feels like this all will take forever. Plus, it doesn't feel like it'll get much easier on the burden of my wife as time goes on I presume.
No offense taken, thank you for circling back and showing your appreciation! As per your questions, here's my opinion.
Regarding volunteer experiences, it doesn't necessarily matter if yours are medical related. You just want to prove that you are a person committed to the betterment of the community and are willing to sacrifice your time to that good. However, clinical experience is absolutely critical for your application. Whether it be volunteering, shadowing, paid, etc, you need to support your decision to pursue medicine with actual time in a clinical setting, interacting with patients while seeing what the role of a physician is like. Being a social worker, I'm sure you have countless hours with 'patients/clients' which does help, however you will still need some clinical experience and you can get this in a variety of ways... If you have a good amount of volunteer experience I'd suggest contacting some Docs in your area, introduce yourself with your resume, and ask to shadow. Don't go to a random hospital, ask to volunteer, and spend a hundred hours in a gift shop... not going to help you much. Getting actual volunteer clinical experience in a hospital is becoming incredibly more difficult, especially without credentials like an EMT or CNA.
As per research, it need not be medical related, but should be empirical in nature. Research isn't a must, but it's definitely an advantage to have it.
Did you say professional rock climber? Awesome... I'm just on the other side of Tahoe and do my share of climbing and bouldering when I get the time, which is rare anymore, but I have had a good number of days on my mtn bike this summer.
As far as success in med school, don't believe you have to take upper levels to be successful or to have some sort of "greater appreciation for the material." That's just silly. Med school is just wrote memorization BS - nothing more, nothing less. You don't have to be a brain surgeon to understand the majority of material in medical school. Yeah, I struggled in anatomy, but I got a solid high-pass in it despite my struggles - it just took me more time than most others. I actually had one of the highest scores in my med school in genetics despite never taking it before. I honored microbio despite never taking it.
In my opinion, your time is much better spent on diversifying your app w/ volunteer or research or work experience or MCAT studying or re-taking classes with poor grades or whatever over taking a boring class that probably won't help....and getting a B in an upper level class will certainly hurt you. High risk, low reward, seems like a no-brainer to me. Studying for the MCAT is the best way to get a better MCAT, not taking cell bio.
I'm not meaning to challenge your perspective, you have valid points especially in considering the most valuable use of time, but I've heard contrary statements from the cohort of med students that I have the luxury of gaining advice from who seem to think the UD courses like biochem, metabolic regulation, immunology, virology, A&P, etc. gave them a pretty big advantage going into certain blocks, simply being that wrote memorization is easier after seeing material twice and already having the concept down. That said, this sample of students only includes those from a school which requires upper division sciences for acceptance, so it's difficult to compare with the perspective of someone who took the minimum standard pre-reqs and determine if either are truly better off. As a screening tool for acceptance, I would say it purely depends on the applicant. If like me, they have a fairly mediocre GPA from undergrad (low ~3.xx), then kicking ass in upper division sciences will certainly help prove the question that said applicant can handle rigorous science courses and excel when that is otherwise shadowed by their UG performance. It has been stressed again and again by adcoms whom I've spoken with that for non-traditional students, they would like to see more than the minimum.