Yup I'd say Lyretails are a good option. I have a trio in my 90 and they don't pick on anyone else in the tank unless provoked.
My Female Snowflake clown will once in a while try and chase one away if they get too close to the frogspawn they host but the male Lyretail will jump in and charge the clown.
I have one male and 2 females, they were picky eaters at first but after about 2 months they eat Pellets, Mysis, Brine and flake food as long as they see the other fish in the tank go for the food first and my yellow tang don't say no to anything I throw in the tank.