We did all 4 GG events last year and particularly enjoyed the Fireworks Cruise and Safari Celebration.
The Fireworks Cruise was fun and the CMs were very entertaining on the boat (they do some trivia contests, etc enroute to the viewing spot). They just serve snacks before loading the boat so you don't get a meal with this one.
The Safari Celebration was a much slower safari ride followed by a buffet dinner at Tusker House. This was our favorite.
The Illuminations event was fun but we didn't particularly like the food. The desert and special viewing area for the fireworks show was nice though.
The Good Morning Character breakfast was disappointing. It was your standard Disney breakfast fare (eggs, bacon, sausage, pastry) followed by "VIP seating" for Philharmagic. Nothing special in my opinion and not worth doing again.
At the time we did these the 3 that serve meals were included on the
DDP so we had no real out of pockets expenses for them other than the Fireworks Cruise.
I would do the Safari Celebration again, but probably not the other 3, particularly now that the Fireworks Cruise is no longer an exclusive event.