Vocal delay settings

I like ping pong delay, set to tempo of your song or sync, Left delay at the eighth note, Right delay at the quarter note, 30% feedback. For ballads I'll take the output from the delay and run it into my hall. Delay is less in your face that way.

I see you've gotten the typical "There are no such things as good presets" answer a few times already, and I will assume the wisdom of this answer has made a decent impact.  It really is true.  I will also assume this answer pisses you off as much as it does me. ;)  So here's my take on a practical answer.
 
I typically use delay to create space for vocals in several different ways.  But I will give you an example for use on a focal (read: lead) vocal track.  And even though you will see the setting I used - I want to spend a moment explaining WHY I used these settings so you will be able to create your own spaces based on what you want for the track.
 

 
OK.  So this is a screen grab from an actual track I did recently.
 
First of all I never use the Sonitus delay from a preset.  Never.  It is just too easy to use it intentionally for a specific purpose and get a tremendous result.  In this case I was going for exactly the thing you describe. A subtle delay effect designed to impart space.  Usually I will use timings based on the tempo of the track I am working on.  In this case I used 1/2 and 1/3 quarters on the left and right respectively.  This puts me in a fairly slow version of this sort of delay.  Using metallus' chart above, I would usually be shooting for something in the 40-120ms range, but this track sounded good with the 1/3-1/2 setup.  More often I will land in a 1/3-1/4 setup or 1/4-1/8.  Generally I will flip through some of these sorts of settings to see what sounds nice in the track.  It is important to note that you MUST use asymmetrical r/l timings to create space, although locking a (mono) single timing can also sound "right" if you want that.
 
I will usually bring feedback and crossfeed (which is just another feedback but one that blurs the image) down fairly low.  Often I will put them up a little higher than what you see here, but I am mitigating the longer delays in this case with less regen.
 
The filter setting is also important.  We just don't need to be creating any excess buildup in the <500hz range usually, and frankly it is also slightly anomalous here that I have a lower than usual  highpass @`200Hz.  It sounded good with this guys vocal.  And I usually want to cut off most of the frequencies above 5-6k especially avoiding the sibilance range for the singer.  But again this is TOTALLY taste dependent for the singer/track/production.
 
While I am tweaking these values I will have the mix percent much higher than the 6% I landed on here....  then I will adjust down to taste.  6% is in the lower half of my usual range for this purpose.  Again this most likely is chosen in part to mitigate the longer delay time.  Sometimes I am up around 9%, but rarely will I end up in double digits.  At least not for this purpose.
 
Now...  this was a lead vocal.  Had it been a BGV, I might chosen  similar settings overall, but diverged with the filter and timing, and I usually would create an asymmetrical panning for the right and left channel unlinking the r/l amounts and doing something like 7%/13% or vise versa.  I can be more generous for BGVs with just about all the settings.  I will make timings longer, filters less draconian, and regen more generous.  And especially I will push the mix slider to the right more than I will on a lead most of the time... Also in the spirit of the stereo image I'll put (much) longer/louder delays in the opposite channel from where I've panned the BGV (especially since the effect is usually pre panning)... but then I am a sucker for lush soundscapes.
 
Hope this helps.