Couple of comments :
1) The SSSS thing is definately NOT RANDOM.....And it does indeed mean a bit of a third degree interrogation/search, I know this because it seems I am always flagged with this when flying out of the USA.
2) The ammount of hassle you get from US immigration does indeed depend on the port of entry. Agree that DFW/Houston have the most friendly staff.
3) Before the US ramped up security/immigration/Visa hassle to foriegners my company did virtually all its training courses in the USA. Now it does almost half of this training in other countries such as the UK and Dubai.