I think I recall a documentary on the Beach Boys up on youtube (the production of Pet Sounds maybe?) where that technique of blasting the material into the "echo" room and rerecording it was discussed. It was some music documentary anyway. Pretty cool.
 
In regards to the Grand Canyon effect being delay as opposed to reverb... wouldn't that actually be more of a really looong reverb because the slapback is caused by reflections instead of actually delay a second signal?
 
Obviously I'm still learning the differences so feel free to slap me (just be gentle... I'm frail).

tlw

BeepsterI thought that's what reverb was until I started really getting into recording and messing with all the verb plugs/sims.

I have a 1990s (reissue) Fender valve reverb tank fitted with NOS valves. None of the guitar sims come close to getting that sound. Maybe because few people own one, so few people really know how it's supposed to sound and react to the guitar and amp. The GR and Amplitube "models" are weak, thin, tinny and the dwell and mix get too excessive far too quickly. The Fender unit is warm, squishy and boingy and the "models" simply aren't.

Overloud's Springage is the best spring reverb plugin I've found so far. Not quite the same but very good in its own right.

Springage is indeed a very nice unit but I've had a hard time dialing it in because I didn't know exactly what I was doing. Should be much easier now.
 
As far as the GR5 verbs I don't think I would actually use those too much for actual final mixes (what with all the much nicer verbs in Sonar) but it was eye opening. Really I found the simplest one to be the nicest sounding one which is the LittleVerb (or whatever it's called... I think it's meant as a play on Little Wing). You can't dial it in. Just press buttons to get two styles of reverb of varying intensities.
 
Some of the delay units actually almost seemed to work better than the reverbs. IIRC some actually had built in reverb that could be blended in. Still I think it would probably be better to just use the Sonar tools (aside from some of the crazy reverse tools the GR units have... don't think I could dial that in on a regular verb/delay).
 
The one really cool one under Special FX though is that Grain Delay. That does some weird stuff. Pretty extreme but fun to play with.

All I know about Lennon's vocals is that Paul mimicked him perfectly in " Let Me Roll It". I'll have to listen more closely to delay vs reverb, as I only listened for the attack to be repeated to tell if it's delay. I didn't pay attention to focus.

Beepster
Some of the delay units actually almost seemed to work better than the reverbs. IIRC some actually had built in reverb that could be blended in. Still I think it would probably be better to just use the Sonar tools (aside from some of the crazy reverse tools the GR units have

The Roland Space Echo is probably the best known combined (tape) delay and (spring) reverb. Another unit with a unique sound and feel.

As for delay rather than reverb, lots of guitarists who used Marshall or HiWatt amps that lacked a reverb used delay to fatten their sound, especially when analogue delay pedals became available. Usually set to the maximum delay possible, around 300-350ms all the time. For some reason a 300-350ms delay with low feedback and a moderately low level works on guitar as a thickener pretty much regardless of tempo.

Reverse delay is one of those things that is best kept for the few times it works. Not that I've ever found a time it works for me. Apparently Neil Young uses (or used) a cheap Alesis Microverb's reverse delay set fully wet with no dry signal at all for when he finds his usual grungy Fender reverb unit not sufficiently over the top.

tlw
That Ronstadt version is much weaker than the original and that thin, metallic reverb doesn't help. There was a fashion for swamping things in that kind of reverb at the time though, not just voices but acoustic instruments as well. It's meant to make things sound "bigger", but unless done very carefully wipes out all the gaps and transients that are necessary for rythm.

I don't think it's lacking at all. It's a totally different take on the song and isn't trying to compete.  I like them both.  The reverb is probably an early Lexicon and sounds quite nice.  They don't need a lot of transients in the arrangement.  It's being done as a ballad and isn't supposed to be rhythmic.