No Honor Guard experience, but Command Squads are amazing units and I include them on all my lists from 750 points up.
I use them close combat oriented, with Company Champion, power weapons and a single power fist, mounted on a Razorback with my Captain, but they can be tailored to almost anything you need it. You could have a unit with 2, 3 or even 4 meltas with melta bombs and start popping every single tank around. If you really want to insult your opponent, take bikes for extra mobility.
The Apothecary is great. Heck, FNP is awesome. I wish I could buy them as an upgrade option for every squad.