Fantasmic - Yes, Disneyland's is by far better....there is just something incredible about haveing this show rise out of the areas you've been walking through and playing in all day...plus the Peter Pan scene in hands down better than Pocahontas!
Having said that, it is still worth seeing MGM's. It is kind of a nice change to sit on a bench and enjoy the show without having to peer over people's heads or have people pushing up behind you. And little kids get a clear view as well. MGM has dinner packages that include seating at Fantasmic. The seats are way over on the side, but truly, (in my opinion) any seat is good, and it beats having to wait an hour and a half (I think you need to be there 45 minutes prior to the show starting.)
Also at MGM DO TOWER OF TERROR! It is better than ours...and has some really neat effects. Don't skip it thinking that we have our own here. The line itself is worth it (the outside part.) (You can usually get a fast pass to Rockin Roller Coaster and then go ride Tower of Terror while you wait to use your fast pass. - In my experiece, that is the better way to go, as the Terror Line seems shorter becasue it is more interesting...)
at EPCOT - Take an afternoon/evening to not eat dinner and just walk around the world showcase and sample stuff. I especially love the Fish and Chips in United Kingdom and the pastry shop in France. Enjoy the little street shows they have in each country...even if you only stay for a few minutes...like the living statues in France or the acrobats in China.
At the Magic Kingdom, its fun to compare our rides to their's. Sometimes there are just little subtle differences. Other times there are whole sections added or missing.
Animal Kingdom - Kilamanjaro Safari's was already mentioned. Also, try Dinosaur...while interesting, it really makes me appreciate our Indiana Jones!
You are going for ten days....that is great for your first visit. Take it easy. Park Hop....go to one park in the morning, rest or swin in the afternoon, and go to another park at night....when I first went, I thought "no way, I'll just go to the same park each day" but my friend talked me into it, and it was quite a fun experience to mix it up.
Oh look into any resteraunts that sound appealing ahead of time. You may want to make some priority seatings before you leave. We like:
EPCOT: The Garden Grill and Marakesh
Animal Kingdom Lodge: Boma (and for a good counter service - Tusker House)
MGM - The Brown Derby, The Sci Fi Diner (usually for desert)