Where's my Randall's Shrimp?
With the other critters in your tank, I would expect to hear some popping from the shrimp at some point. I regret not going with a tiger as well but I stay hopeful that it'll eventually pair up with the goby.
As far as fish go, I can't say enough great things about a tail spot blenny. They have a quirky blenny personality, stay pretty small and are colorful compared to other blennies. The couple that I've had were also not aggressive at all. I currently have two two spot bimaculatus blennies. They're characters and I enjoy them but I wish I had went with another tail spot. The two spot blennies are super tiny (they look like minnows) and aren't as colorful but they do have that blenny personality.
I also currently have a Helfrichi firefish that I love! I really didn't want to pay so much for a small fish but my wife picked it out so I took advantage of her not being able to blame me for spending too much on something.

I'm glad I got it though. I've had other red firefish before and zebra barred dart fish and I've liked them as well, but the Helifrichi isn't near as skittish and is just super colorful and always out swimming in the open. The other dartfish I've had would bolt in the rock work if I moved to quickly. The only time this guy hides is during a water change, when I'm adding water back into the tank. I can walk right up to the tank and put my face up to it and he'll just stare back at me. It's been a very cool and personable fish. I'm not sure if they're typically like that or I just got lucky. Either way, it was well worth it.
Some other cool small peaceful fish are Banggai cardinalfish. I always thought they were boring but after having one, I really like them. I've had a couple of Possum Wrasses as well. They're really pretty but I've not had good luck with them. For whatever reason, they didn't live long and hid the entire time. I will say that the Tanaka Possum Wrasse is a looker for sure.
Good call on avoiding the six line. I made the mistake of buying what I thought was a pink-streaked wrasse but was actually a scarlet lined wrasse. The LFS has it labeled a "œpossum wrasse" which I knew it wasn't but I thought it was a pink streaked wrasse which are supposedly peaceful. The scarlet lined wrasse isn't super aggressive but it does bully the helfrichi and banggai some. I've noticed a couple of times there's been a small "œbreak" in the helfrichi's fin and I've wondered if the wrasse caused it. He's kind of a jerk about it too. He'll just dart out of the rock work and start being a bully but other times he'll swim along side them like he's not sure if he's a wrasse or not. I've been debating taking him back to the LFS so it's good you're not making the same mistake. The worst thing is to gaze into your peaceful tank only to have one butthole ruin it by being a bully.