Which do you have your cable set on?
"as stated above, it will default to broadcast setting"
FALSE!
If you don't set your box right, it won't default to the broadcast setting, it will default to the best available setting you have told it.
"If you have 1080 tv, why would you set it to less than that?"
ANSWER!
Many people believe that 1080i is a better resolution than 720p but they are wrong, and here is why.
The difference between 720p and 1080i is "p" stands for progressive, and "i" means interlaced. So 720p means that the broadcast is showing 720 lines of resolution at once. Each line scans directly below the next. (They progress) Interlaced means it scans every even line first, then goes back and scans the odd lines. (That's why sometimes a tv or computer monitor will look likes it's flickering, or a line runs constantly from top to bottom when you see it on video. The scan rate is different than the video camera) Anyway, 1080i only displays 540 lines of resolution at a time (because it's interlaced) 720 is more than 540 so 720p is a higher resolution, cleaner picture. If you have the option, choose 720p. Most TV's now have 1080p, which is obviously, even better. I don't know of any broadcasts in 1080p. That resolution seems to be relegated to blue ray (maybe Netflix, I've never checked)
Unfortunately, you normally don't have the option to choose. Most networks broadcast only one resolution, and you should select whatever resolution that's broadcasting. ESPN broadcasts in 720P on TWC. If you don't have the 720P option turned on on your HD box, it will automatically downgrade resolution to 1080i or 480p.
Long story short (too late, I know) you should choose all the available resolutions available on your cable/sat box, or "automatic" if that option is available.