To get dd1 to suck we either "helped her" by putting a finger on each cheek and pushing, making her make a "suck" or we dipped the pacifier in gripe water making her take it.
She used the hospital soothie pacifiers. They're very similar to the avent soothies and I think are most "nipple-like".
DD2 does not seem to be as pacifier-happy. She sucks at her hands and bobs on me after she's done eating (if I put her back on the boob, she just sort of sits there, so I know she's done" but I can't get her to take the pacifier.