They will tell you it's based on when you reserved the table, but it's also dependent on other factors such as party size. Unfortunately, no guarantees of what row you will get and showing up earlier doesn't make a difference.
They don't start setting up the tables until an hour? Maybe a half-hour before check-in, so it would be too late to cancel. Most of the views are good. I understand your frustration, though. You're not ungrateful. The people next to us had their view blocked because the table in front of them (first row), had his phone up above his head and blocked their view. It was unfortunate, because the table next to us had smaller kids. I didn't notice until the end that the reason they kept moving around was so they could see around him.