I've only done the pre-party and watched from the Hub. The view from there is straight on to the castle, so you can see the projections and fireworks as they were intended to be seen. There are a few random light poles and short, skinny trees that will be in your sight line no matter where you stand, but they aren't big enough to affect the view substantially. There is no place to sit, except on the ground before the show starts, and the CMs ask everyone to stand when it begins. I haven't done Treats and Seats, but from what I have gathered, the view is somewhat off to one side, so the projections aren't as visible, and the fireworks don't "frame" the castle, and you don't get that full effect. I imagine it would be nice to have seats, but I think there are some drawbacks visually. There are a couple of threads that discuss the dessert parties in detail, and there are pictures on those that may help you make a decision.