More padding probably won't help. Bike saddles want to support your "sit bones". Adding more padding is just more "stuff" to be squished between your soft tissue and the saddle. Your sit bones are still going to sink down until they find something solid that won't move. I have the same problem on the stationary bikes at the Y. They have a relief channel, but they're so soft that it's not really effective. I nearly always wear padded shorts, but I'd prefer a harder saddle.