I've done several extra events. In order of what I liked most to least (although not really least, I liked them all).
DAH - Did this at MK in August and it was amazing. We covered so many attractions and the park was empty, we waited for nothing. I can't wait to try the DHS and AK version of DAH (hoping dates get extended into our trip next year).
MNSSHP - I love the party exclusive things like the shows, fireworks and parades
Star Wars Galactic Spectacular dessert party - Now that they have added seating to this party, it is my favourite of the dessert parties.
EMM Fantaslyand - I love 7DMT, so being able to ride it 10 times in a row in less than an hour, is amazing. I also find the breakfast buffet here pretty good. I also did the HS version 3 years ago and loved it, so I imagine the current one with Toy Story Land is probably great too. I'll be trying it on our next trip.
Hallowishes Dessert Party - really liked getting samplings of all the exclusive party snack options
HEA Dessert Party - I've done the terrace version and the after party garden version and both have their benefits. I love the terrace because I like to be able to sit and relax and have my desserts. I also really like the after fireworks garden version because it takes up a lot less time, but with the full benefit of the same food.
Frozen Dessert Party - I like the seating and the food at this party and the table along the water for Illuminations is really nice. I only rank this one below the MK party because it's less difficult to find a good viewing spot without the party seating at EP. Also, the Frozen ride is not a draw for my family at all. If you have Frozen fans, then I think the value of this one goes way up the list with the exclusive ride after the park closes.
I've also done some tours, not sure if you were looking for feedback on those as well
Family Magic Tour in MK - It's a guided scavenger hunt through MK that is prefect for younger kids. I would say age 5 - 8 is the sweet spot on age for this one
Family VIP Tour - I think this one has changed a bit from the one we did a few years back, but it's 7 hours guided through key attractions in 3 different parks. It is great for kids or those who aren't into the more thrilling type rides
Ultimate Night of Adventure at AK - Loved this tour so much. It's not a tour so much in information shared, it's more a guided group through the fastpass lines of all the main attractions at AK, but you do get the benefit of guides who like to share their experiences and some Disney info. It includes food from Satu'li Canteen and reserved seating for ROL. A great way to cover a lot of ground in AK in just 4 hours.
Caring for Giants - Backstage tour of the elephant area of the Safari, led by one of the elephant keepers. This is a great experience for dabbling with tours because it's only an hour long and relatively inexpensive at only around $30/person.
Behind the Seeds - This walking tour through the greenhouses at Living with the Land is a great add on if you enjoy that attraction. Like Caring for Giants, it is a short and inexpensive add on.
Wild Africa Trek - This tour is fantastic! Climbing the rope bridges over the crocs and hippos gives you a great perspective on the animals and the tour guides are amazing here. Also includes a nice snack out on the savanna.