If you're going to the Piggy Bank, continue on the dirt road for a ways, and look for a trail straight up to the cliff just after the road takes a gentle left turn. For other walls at the Bank (eg. Surreal Estate Wall), take the right turn shortly after leaving the parking lot, and follow a trail straight across the valley to roughly in the middle of the entire bank wall. You can go left for Surreal Estate Wall...etc, and right for 2150 Wall and The Vault. The Vault starts when the cliff makes a 90 degree turn north. From the north end of the Vault, you can connect back to the Cactus Cliff trail.