So, in each of the parks, what are some things you would suggest someone does who have experienced all the “main attractions” (the rides) that might be otherwise overlooked.
While watching a DFB episode recently about “secrets” at the MK, I was surprised that of the ~30 secrets she listed, we actually only knew about 2 of them! So, this made me wonder about what things we’re missing.
Just as one small example: In all the times I’ve been, I’ve never seen Walt Disney:One Man’s Dream.
My family has never seen the Tiki show, Country Bear Jamboree, or the Electrical Water Pageant. I recall seeing them a gazillion years ago. We’ve never ridden the Liberty boat.
I’ve never seen Walt Disney:One Man’s Dream either. Or, the Pixar mini films at Epcot, or been to Club Cool.
And confession time - I’m so adamant about NOT doing Mission Space that I can’t even tell you where the ride entrance is. I just know it’s “over there” somewhere. Minor PTSD from the motion sickness it gave me 20+ years ago!
I don’t know how much ‘‘lesser known’’ it is but for our 2nd visit we did ‘‘pirates of the 7 seas’’, which we didn’t know about during our first visit and I think it was our son’s favorite thing of the entire trip !
Maybe a good frame of reference would be that if you saw the abbreviated form, you probably wouldn’t work out what it means. POTSS or POT7S? I’d have no idea! 
So that would qualify. Similarly: WD:OMD? I wouldn’t know what someone meant.
planning on MK “kiss goodnight”, village haus “wish book” and phones in Le Chapeau next trip
We did Colortopia in Epcot last trip. We actually had some fun doing that. My kids really liked the “magic” paintbrushes.
We did 1st Hair Cuts at the Barber Shop on Main Street. Loved it now, we always try to fit the barber shop in.
I’m 46, so like 45 years too late for that. 
But interesting idea, nonetheless!
They will still cut your hair and add sparkles
watch a dapper dan’s full performance along with the citizens of Main Street? Also the same thing in HS.
Um. I might be into Disney, but I’m not sure I want Disney to be that much into me!
A 46-year-old man with sparkles in his hair? Um. Yeah. No. 
EP: The model train that runs outside Germany. The Stave Church at Norway. The Tomb Warriors at China.
Magic kingdom
Read thw tomstones around the haunted mansion and see the pet cemetary. Solve the mystery of the busts on the haunted mansion in the line que before the stand by and fpp split. Look for the ring in the outdoor line wue as well
Search out the hidden pascals around and across from the tinkle towers.
Search for the nautiuls in the wue of under the sea and the giant squid on the weather vane for dvc across from under the sea.
Ride a main street vechicle. Listen into the lessons in the alley iff main street by the jeweler. As @Randall1028 said catch the dapper dans.
In picchino village haus watch the iasw boats.
Explore tom Sawyer island
AK
Divine
Winged Encounters
Harambe Acrobats
Discovery Island Trails around Tree of Life
Exactly the same for us, apart from the liberty boat.
Definitely not lesser known but we’ve never been on the railroad either, and won’t this summer either.
I find it fascinating the things different people gravitate to and love and equally the things people avoid.
I don’t know…maybe rather fetching with the underpants. They are from Paris afterall.
Yes, yes. But the phrase is “when in Rome” not “when in Paris”.
We’ve never done the Frontierland shooting arcade. Looks like fun but we never have the time.
The mini golf also looks like fun but we believe in day breaks not break days and we can never fit it into the schedule.
Not exactly unknown but we’ve also never done O Canada! for some reason we always start the WS on the Mexico side (Frozen is probably the reason). By the time we get to Canada we want to leave.
One of DD5’s favorite things to do at WDW is the pony rides at Fort Wilderness. There’s absolutely nothing that screams “Disney” about it, but she loves it and it’s a nice break. We usually give her half an hour or so at the FW playground after, before taking the boat to MK.
Oh, right. We did O Canada! when I was like 9, and never again…mostly for the same reason. We seem to always start on the Mexico side. I think next trip, I’ll plan to start on the Canada side instead to remedy that!