For additional troubleshooting, disable all your power-saving features altogether. Then start adding one at a time over the course of a week or so. Enable monitor power-saving first -- see if the video card wakes it up properly. After you test that a few times, enable disk-drive power-saving. Test it. Then, test system standby or sleep or hibernation, whichever is appropriate. This will help you narrow down the issue to a specific piece hardware.