Ok actually lots of places.
Place 1: Blackburrow, doesn't mean much anymore as I'm not there a lot since
passing 15 but doing Lullaby around the Elite Guards would draw every Burly
gnoll and Gnoll out of the woodwork.

Place 2: Paw, same problem basicly, but I still hunt Nobles and Commanders
here as well as the named guys. I dont want a bunch of green guards jumping
in while I am fighting the commanders or named Shamans.

Place 3: Kerra Isle, I draw the blue Clawknights and Pridesman and
Priestesses usually, lullaby here would also bring on hordes of males,
females, and huntresses.

Place 4: As you noted the outdoor zones, especially the bandits in W Karana.
I'd love to use lullaby on the caster groups so we can sweep a bandit camp
and move on, but all it takes is a couple of who green grizzlies and things
get out of hand fast.

Place 5: I can't imagine the nightmare this would cause in Crushbone as
every green Centurion in range started stunning me.

Anyways, these are the situations that come to mind most.

Kitasi of E'ci