Fezz, I don't know what those E's were doing at the time, but there are situations where it's not appropriate to salute, or expect a salute. Check your Naval Officer's guide, it has a good section in there on courtesies (I know most guys probably just toss this book, but mine sits on the back of the toilet, so it gets looked at daily). Basically, if the guys are in a working party, then it's not required, however, they should at least address you. I live in the Q on Corry, so I see various E's all day and I have yet to see one not salute. I've had some Marines stop at the other end of the building stop, salute, and say good morning.
As far as educating these guys if and when they do fail to salute, I believe it should always be done, tactfully. I don't believe in trying to humiliate a guy or make him feel stupid for not doing it. I've heard guys say, "oh don't say anything. You don't know what's going on in that guys head. He may have just had his ass chewed by his Chief or Sgt and he's feeling down". Screw that. When I went through boot camp (11 long years ago) the biggest thing drilled into our head was attention to detail. If that sailor or Marine can't be observant enough to notice an officer just because he's had a bad day, then he may well miss that torpedo speeding through the water or that suicide bomber driving towards him as he's standing watch.