I've set my box to blank screen after 5min idle, and suspend after 10min.
This works well for me, so when leaving my PC alone, I could be assured that it switch itself into suspend to save some energy.
Just sometimes, I like to hear some music, or hang out in a IRC channel, or doing a take long time compile, then, I don't wont that my PC goes into suspend mode, even when I leave it alone for some time.
True, I could switch suspend on/off in the energy settings, but I found it unpractical.
So I wrote a little tool to avoid suspend or shutdown on privileged level (e.g. root) when a running user process shouldn't be interrupted. It's nosuspend.
Usage nosuspend, simply run before another command as in: nosuspend appname -parameter for appname
Full bash completion is supported for easy command substitution.
nosuspend use a PolKit rule allowing active users to set the systemd-inhibit flag with UID 0/root priority and avoid this way that the PC could suspend or shutdown during the given app is running .
It has a "secure" mode, where you must enter the root password in order to run it, and a "relaxed" mode, which ain't require password. The mode needs to be selected during compile time.
Maybe it is of some use for the one or the other here, you can get it here:
https://github.com/brummer10/nosuspendregards