So I went straight to underwear again. They both excitedly donned their big kid underwear and did okay. I altered strategy a bit and decided to reward dry pants with gummy bears too. (The little one really likes this idea as she gets a treat no matter what.) This worked okay. My son peed in the potty when asked, but usually dribbled in his underwear before he went to the bathroom and never went to the bathroom unprompted.
My daughter can hold it like the Hoover Dam. She seemed to sense my brain waves about asking if they were dry. When I would go to ask her if she was dry, I would find her with soaked pants and standing in a puddle. Maybe the smell of gummy bears inspires her. I was about to offer her one, but found her standing on her potty (with the top closed) in a puddle. <
They couldn't wait to show their big kid underwear to their dad when he got home from work. As soon as they heard him come through the door, they ran to greet him and whipped down their pants. My son proudly displayed Mater on his bum. My daughter was a little too enthusiastic and yanked down her underwear too, giving her dad a big moon as a welcome.