I am flying to the US at least 12 times per year. My experiences with immigration are negative with vast majority. Airports also vary, ORD, LAX, JKF and MIA are consistently bad. BOS is ok when you get in as 1st int'l plane. Both depart from the assumptions that there are good guys = US citizens and terrorists = all others. There is also the rule, that they work slower as longer the queues are. Bear in mind that they hired all employees from low cost private agencies and made them state employees. The good news is that they all have medical insurance now.
It seems that the newer Int'l airports like PDX, CLT, DFW are treating us "aliens" with a little more dignity.
For a certain time travelling into the US via Canada was easier and friendlier, however recently I had in Montreal the most rude and unpolite US immigration officer I have ever come across. He even had the same name as the airport.
Flying in the US domestic is easy as long as you book a return ticket through a US company, pay it with a US credit card and show your US driving license as photo ID. If you are travelling on an international ticket with a non US passport you are immediately classified as pontential terrorist ( even when you are 85 years old). in this case your ticket is coded SSSS, which means that you are subject to "special" treatment, which can easily addd 45 - 60 mins at security. I have never met in "special" queue US citizens.
My family , wife, parents and kids, refuse any proposal to vacation in the US after repeated unfortunate experiences in the past years with Homeland security and TSA staff.