I recently took an incredible 6-week commercial voiceover class with coach and casting director Roger Becker of VO Syndicate, and had my demo made with Jeff and Andrew from Ape Sauce Productions.
I can't. Recommend these people. Enough.
Jeff not only helped me choose a variety of material for my demo, he also coached me through each spot and gave me fantastic notes to strengthen my reads along the way. Andrew also gave me some fantastic coaching and advice to think about for my future career in voiceover work. For more on my class with Roger, read my post about his class. Give it a listen and let me know what you think!