Are you talking about the Waves ADT? I think this is a good idea for this track and will help add some vocal width. I would reach for the Waves ADT over a doubler, micro shifter, or Eventide H3000 emulator because it sounds less chorusy. I’d start with the Stereo Wide preset with your vari-speed set around +/-17ms and pan hard left and hard right on the wings. I think this is a really good idea because that vocal is definitely lacking width in my opinion. But use the V2…not the V1 because it gives you more control over the stereo image.
I would try mixing in a dark saturated drive first. If you have a Sound Toys Decapitator, this is a really good candidate for that plugin because it lets you control the contour of the saturation. I feel the dry source needs some warmth too. If you have a good 1081 Neve emulator I would throw that infront of the LA2A. The Fab Filter Saturn could really help because its a multi-band driver. Another idea is to take a multi-band expander and feed it to a drive/saturation plugin. Basically you want more warmth and saturation if you can get it.
I partially disagree with what @Paul999 said about verbs earlier, but only as a matter of personal preference and taste. I would send the piano and vocal to stack of several verbs like @ColdRoomStudio mentioned. The vocal is too dry for me right now, but this isn’t to say that he’s wrong…its totally a preference thing. If you have the Waves Bricasti, I think I’d start there. If not I tend to favor the Phoenix verb and the UAD EMI plates. If you don’t have those, it may be worth demoing some stuff in the Waves Abbey road collection. If I recall correctly Paul uses the Tsar (or was at one time). Its pretty good. I used it for a long time but stopped when I got the Bricasti set up. Also, if you have the Slate bundle, he has a Bricasti emulator in there, but I prefer the Waves one if you have it.