The point of the UAC prompt is not just to be (slightly) annoying, it is to alert you when some thing (malware) wants to make a change to system files (or another action that could be malicious).
So, if a UAC prompt suddenly pops up and you didn't do anything, it is likely it could be malware.
Naturally, turning this up will increase your UAC prompts, but (theoretically) should be more likely to catch malware doing something it shouldn't.
If you are already using a standard account for normal use, and have UAC on, you should be fine.
There would be no harm (only annoyance) in turning it up higher.
I don't know that there would be a lot of added protection, but it is there as an option.