This is so nice! :D
I think I'd just put a dynamic eq on the intro guitar. Get a transient processor to smooth a some instruments out a little bit, and possibly give some sounds automation with reverb that's super quiet to fade in the start of instruments and add to the overall smooth vibe.
Around 1:40 the high piano makes things a bit cluttered for me. I feel it'd be better if that piano was quieter but had the highs saturated to just add some presence. I also think the piano around 1:52 is a bit too loud, it kind of adds mud and is dissonant with the vocal harmony.
I think the sliding sound around 2:05 would be nice to just be band passed around it's resonant frequencies really quiet and you could automate it off to fill back in around 2:45
I really like this and hope any of my opinions help you! You probably mastered the song already but I thought I'd give some feedback anyways, good luck with your future stuff!

Thanks Syndice! I actually haven't mastered it yet. I've taken a break from it to reset my ears and also wait for any feedback from here, so your input is greatly appreciated.