M.,
My daughter was easy. I was pregnant with my son and I didn't want to have 2 in diapers for very long so I started PT'ing with her very early. She loved books and so we spent long periods of time in the bathroom with her just sitting on the potty chair reading books. When she went, we did M&M's. In the beginning she only got 1 and then one day after she got her single M&M, she stuck out the other hand and said "and this hand." So that started getting 1 for each hand.
She was potty trained by the time her brother was born. She was 16 1/2 months old. Oh and a plus was she knew her ABC's and could recognize them as well.
Her brother was barely 2 when we potty trained fully. He'd been peeing on the potty chair and would not poop. One day I knew he needed to go because he'd not gone for 2 days. I put him on the potty chair and I told him that if he'd do is big job on the potty chair we'd go get a Barney tape he wanted. (this has been almost 13 years now) He came to the living room 2 minutes later announcing he was done and grinning ear to ear. I checked and he'd actually gone. We cleaned up and went to get the movie. 2 days later we were in the same boat, however he didn't get another movie, but he did go in the potty and after that, we never had another diaper and amazingly he NEVER had a bed wetting incident. It was a week later, I realized I was on a new road with my family and we were done with the true baby years.
Good Luck,
C.