nectar is my favorite SN lippie. i don't think of tender as a cool color, but nectar is a little 'warmer'--more red/brown, but sooo pretty. on my lips tender is very sheer and it just gives them that little pinky brown shimmer, just like the description.

rhapsody is also browner and has more coverage since it is a black label, but is still somewhat sheer. it's a reddish plum brown.
rare berry would be too bright for what you are looking for, and i think pout would be too cool if tender is cool on you. i don't have sweetheart so i can't say about that one. breathless is nice--neutral pink with good coverage (almost like a lipstick).
as far as a "berry" for you--i'm not sure what to recommend. berry nice is certainly a dark berry color, but it has no brown or shimmer--just a dark stain (i really like the non-shimmer kisser slicker formula though). figment is a nice plum color, but also has pink. it's warmed up by a copper shimmer.
hope that all doesn't make it more confusing--if i were you, i'd definitely try nectar!!