Freddie, guitarist Brian May, and drummer Roger Taylor all contributed greatly to Queen's barber shop quartet meets Led Zeppelin harmony assault. Some tracks feature more of one than the others, but frequently, especially the "choral" arrangements, were all three.
Warning: this post will be mostly dealing with Bohemian Rhapsody in detail.. if not interested, move a head to next post
I happen to have a 24 track dump of Bohemian Rhapsody (dumped directly from the original 24 track tejp, track for track to wave) pre mix and pre-eq/comp.. and although there are bouncing a plenty in sections of backing vocals, it is as close as we'll ever get to hear how that song was "compiled"..... I can certainly testify of it not just being Freddy, although he does a LOT of the takes on that particular song but it is very clear that both May and Taylor are all over it too (not just the obvious bits)... quite interesting to go through the tracks and see how it was done back when..
Backing vocal wise, they all sing each others parts (apart from the very highest Meeee before the heavy part, which is just Roger T. But otherwise, it seems like their "standard approach" to to at least have 3 parts but all those parts are sung by all 3 making it a 9 part layer as a bare minimum.. than it swells out from there LOL
3 tracks for the bass... one DI, one close cab and one sounding as it was about 7-10 meters away in the room... another area of interest is the 5 different lead vox takes that remains .. (and as was standard back when, if there was a "hole" in a track, it was used for something because tejp realestate was pricey

so a track called lead guitar had some vox parts when the May isn't playing and so on... One highlight for me was to solo the "shivers down my back" response thing which I always thought was piano and strumming along the strings, but it's actually Brian May who is playing a part and when in isolation, the part actually makes a lot of sense
If you have any questions regarding the song and how it was done....or want to hear any particular part in isolation, I can arrange it... I will however not share the whole track as there would be black cars with an armada of Queens lawers arriving

The dump is in high res and could be "misused" if it got out.. but I'm more than happy to share "bits" for educational purposes ... if so, pm me..
anyhow.. + one for Queen and ELO... if one with great harmonies also mean how they are made up in terms of counterpoint and not going the simplest most obvious line.... Journey (which I love) sounds great but they are for the most part quite obvious and "natural" 3rd above and 5th below...
Eagles, I've done an Eagles tribute show and it was my task to pick out all harmonies in 20 of their songs.. and as good as it sounds, there's a lot of rinse and repeat.
