Fantasmic - When we went they seated us in the middle by the Dining Package folks and it was great, but soon after they started sending FP+ folks off to the sides like everyone else. Unless they have changed it back I can't see wasting a good FP+ at DHS for a seat I could get myself with only a few minutes added. When I went they actually allowed Standby to enter before FP+ and once we could we had to scan which slowed us down. Without reserved seating, not worth it. (NOTE: The Fantasmic Dining Package is a great way to come closer to show time and sit in the best seating in the stadium).
The Fantasmic Fastpass has been inconsistent.
Some people have been in a reserved area and other nights, they have not used a reserved area.
The advantage we felt was that you entered thru a dedicated Fastpass Plus entrance, so not with the large group of people.
But, even thru the regular entrance, once the gates open, the crowd thins out and it's more small bunches of people, so not walking in a huge crowd.
If you are using a stroller as a wheelchair and your child is staying in it, the wheelchair will be in the back row with space for one of your group to sit next to him and the rest in the rows in front. That arrangement of wheelchair seating is the same across the whole amphitheater, so there is wheelchair seating in reserved and non reserved areas.
There is also some wheelchair seating in the very front row, but a very few places and I would not recommend for someone with sensory issues - you will get splashed or sprayed on and can feel the heat from the fire. Plus, there is no easy and quick way out.
Wishes - We loved this, personal space, seated on grass in rose garden, no rush. So nice! But, if you want a direct head on view of the castle with the fireworks in their perfect place you won't get it here. The bulk of the fireworks will be to the right of castle. We are regulars so it was fine for us. The projection show is fine from here and Tinkerbell flies overhead.
As of right now (April 2014) there is construction, with large fences put up, in the castle forecourt area. I'm not sure if the construction affects this viewing area, but it would probably be good to check it out.
From what I have read, the rose garden is being replaced with more grassy area and pavement.
Parades: Day - The spot is across from the Castle forefront show inside the hub. We got there 20+ minutes earlier than our time for each and always a line but we wanted front row for day parade. We did have front but the time in line and then sitting for a long time waiting - got very hot on the walk/road. We got some cool pics of floats with castle behind them but we felt on the curve there that we got minimal interaction from characters, we were pushed about a lot by folks who got there later as with anywhere on the parade route and we would have rather found a shady spot.
Those same things are also issues with the handicapped viewing areas.
For any shows or fireworks, my suggestion is to not be in a rush. Some people leave before the show is over, but the crowd will catch up with you. If you wait a few minutes until most of the people have left the theater/area will give you a much nicer, less crowded trip out.
DAS and Fastpass are meant to be used together for DAS to work best.
Some people have prescheduled a Fastpass to be able to ride a favorite more than once without a long wait.
We used our Fastpass Pluses to preplan some of our must do's and things that typically have a long wait - things like Soarin', Test Track, Toy Story Midway Mania, the new Little Mermaid ride in MK. That way, we were not getting DAS Return Times for those things that normally have an hour or more wait when we were there.
Since the Fastpasses have a window of time for use, that allowed us to plan out some times for other things (snacks, meals, medical breaks) around those 'firm' times and we filled the in between times with DAS Return Times and attractions with short wait times.
And, since the DAS Return Time can be used at any time after the time you are to return, we had flexibility to go later on that attraction if unexpected things came up or took longer than we thought.
That worked very well for us.