Which sleep mode should I use? S1 or S3? I can't have both. I have to set the jumpers on my motherboard for one of them. I wondering what should I use. By the way, do you find sleep mode useful? Do you use it?
I use "hybrid sleep" mode, in which memory contents are flushed to disk but they're also kept in RAM. That means the system can start up very fast without having to read stuff back in from disk. Having a copy of memory also written to disk means you can still resume (although not as quickly) even if the machine looses power.
I generally turn my machine on in the morning and let it sleep when I'm not using it, then turn it off again in the evening. I've used a "Kill-a-Watt" power meter to measure current draw, and I found that my system uses about 8 watts in "sleep" mode compared to about 5 watts when the power is "off" (ACPI computers don't really power completely off).
I actually have a power switching base under my monitor that I use to cut power so that no juice at all reaches the system - after I shut down the machine I throw that switch so that the system really, truly is off and consumes 0 watts.