Nothing says "good times!" like 1000lbs of concrete!
I use square posts around gates; that's what I'm building here. A 24' gate that is at an angle off of the dirt road. A long enough pull-off area that I can be off the road when I'm opening or closing the gate.
The white barrel is the water I'm using to mix the concrete. 2 80lb sacks of concrete at the base of each post. the posts are sunk 3' into the ground; with that amount down, H braced and concrete feet, they'll stay here for many years. I prefer to do the fence right; I've done it halfway in the past and you find out your fence sucks when something goes wrong. Better to do it right and be able to sleep at night.