Space: Above and Beyond
Star Trek: Deep Space 9 (specifically, the Dominion Wars material)
Stargate - SG1
Babylon 5 is on my list of things to have a complete series rewatch of anyway, although that's probably going to be quite an undertaking so I might just pull out the two specifically mentioned episodes (Severed Dreams, S3 and Endgame, S4) and give them a spin on their lonesome.
Battlestar Galactica I've had the box set since last Christmas (as with B5), so I think I'll go with that first. Most of the other recommendations are things I've been meaning to check out at some point or another, particularly the two Stargates. And Star Fleet I've been wanting to see again for ages.
This is going to be fun!
Thanks for the recommendations, folks. If you have any more, feel free to add them here.