Adrianna was one of the only really likable characters on the show. She was a good person at heart, but was naive. Just like we need a good villian (Ritchie Aprile) we need somebody to like and root for, plus she was hot in that trashy Jersey sort of way.
I think its a testament to just how great this show has been when you just look at how many highly entertaining characters have died, been killed, or just disappeared. It still, for the most part, hasn't missed a beat.
Adrianna
Richie Aprile
Ralph Cifaretto
Big Pussy
Tony B.
Jackie Jr. (not likeable at all, but his complete stupidity was very entertaining)
Gloria Trillo
Furio
and of course, Livia
Which reminds me. I wonder if we will ever be hearing from Furio again. They never said that anyone ever found him, only that he ran away to Italy.