For the MK parades, we like to sit on the rocking chairs on the verandah of one of the buildings in Liberty Square (I can't remember which one it is, but you can't miss them). You do need to arrive early, though - about an hour ahead - but it's a good spot to relax and do some people watching. In fact, if they sold beer in MK, there would be no need to move. Ever.
There are plenty of good spots for Jammin Jungle parade and you should be able to snag one quite close to the start time, but our favourite place is in Africa opposite Tusker House. There's a walled flower-bed type thing which you can sit on (it's designed for the purpose) and no-one can stand in front of you. Again, you need to arrive in good time if you want to be sure of getting a spot here. The parade starts and finishes somewhere down near Kilimanjaro Safaris and so passes this point twice. And here you <i>can</i> get a drink at the Dawa Bar (although you need to remember the 'one ID one drink' rule, so everyone who wants one will have to be present when you buy).
The best place to view IllumiNations is from one of the boats which sails from the Y&B marina each evening. Take a look at NativeTxn's IllumiNation Cruise Central threads (on the main DIS Trip Planning Forum) for the month you'll be there and see if you can hook up with another DISer. We've done this three times now. Failing that, you can get to the area where the boats moor up which is just beneath the bridge between UK and France in World Showcase. Sometimes they have it roped off for groups (in which case the bridge itself is another good option), but often it is open. There are steps down to it from the bridge.
For FITS you really need to be somewhere you can see the front of the castle, especially if you want to see Tinker Bell's flight.
