AJ,
In a large enough tank you can keep groups of yellow tangs togther with no problems. Having a tank large enough is the main issue. Some of the most beautiful large tanks will have huge aggregations of yellow tangs, purple tangs, scopas, etc. Sailfins FWIW get quite HUGE. they are a very large fish, I have seen very few full grown sailfins in captivity. Chevron tangs are a great fish, however in my experience probably a bit more docile than most tangs. But all the bristletooth type tangs are great, they stay relatively small don't seem to require huge amounts of swimming room and seem happy to just graze around the aquarium all day.