My thoughts on Mortal Coil, Message in a Bottle, and Waking Moments.
Mortal Coil
This episode is really the 'sequel' of sorts to both Sacred Ground and Coda from Season 3, and gives us some additional nuances to Neelix's character, which, as a fan of his, I really liked. I also liked getting to see both Samantha and Naomi again, and thought the decision to have Naomi be the reason Neelix chose not to kill himself.
Message in a Bottle
This is one of the few episodes of Season 4 that wasn't new to me, but I enjoyed it even more this time around than I did the first time I watched it. Robert Picardo and Andy Dick really play well off of each other, and it's fun getting to see them work together to outsmart the Romulans. I also like the way the writers introduced us to the Hirogen.
Waking Moments
I really liked this episode; it reminded me of several of my favorite episodes of Buffy the Vampire Slayer and Angel, namely Nightmares (Buffy S1), Fear, Itself, Where the Wild Things Are, and Restless (Buffy S4), and Life of the Party (Angel S5), and the idea of aliens attacking the crew in their sleep was a neat one.