Return to Forever is amazing. Of course, Chick Corea can do no wrong in any context.
I also loved Mahavishnu Orchestra. I actually got to see John McLaughlin on his retirement tour, which he co-headlined with Jimmy Herring. Absolutely incredible, all these years later.
Both Jimmy and John are awesome. I have several Mahavishnu albums. Birds of Fire, Apocalypse, The Lost Trident Sessions (which seems a good replacement for the live one Between Eternity and Nothingness which I lost along with the aforementioned RTF compilation) and no matter how many times I try, I just have trouble getting into them. So bizarre...because this type of music is totally up my alley. For some reason it just doesn't click for me. I tried to listen to Apocalypse again just a few days ago (as I don't remember any of the tunes from that one) and couldn't even make it past the 1st couple tracks. I'll probably just have to concede that it's just not my thing. So weird! But it is what it is. Maybe I'm just not "advanced" enough musically to get it.
I have much better luck with other fusion..for example Gary Husband's 'Dirty & Beautiful' Vols. 1&2 never get old. I mention those 2 albums in particular because they both feature John McLaughlin and Jimmy Herring (along with other guitarist luminaries Alex Machacek, Steve Hackett, Wayne Krantz, Robin Trower, Mike Stern & Allan Holdsworth [rhythm guitar only unfortunately -- no shredding
]) as well as Jan Hammer on keys, Jimmy Johnson and Mark King on bass, Jerry Goodman on violin amongst others... an all star cast of players and a really cool blend of tunes. I recommend this to anyone who's a fan of fusion.
I believe Gary Husband played with McLaughlin's live band, but probably only in the UK (as I don't think Gary has the work visa/permits to do any shows in the States). That's a big problem these days for foreign musicians playing in USA. Along with other reasons, with the advent of social media, its much more difficult for this sort of stuff to slide under the radar anymore. I didn't know about John retiring.
A pity for us. I guess we'll always have the recordings and videos.