Well, wouldn't you know it? We only used two cribs for a month (very inconsistently on Amelia's part) before Olivia made the switch. About 2 months ago, Olivia made her first break out of the crib. At first, we didn't worry about it too much. It was very infrequent and after some research, we moved the crib mattress to the floor with the crib still around it. This made it impossible for her to climb out of her crib for another month. Once she figured out how to climb out this second time, she kept climbing out. We knew that it was time to make the switch.
We tried to make it an exciting thing for Olivia. We talked about her big girl bed and the fact that we were going shopping for her big girl bed. We made the trip to Ikea and headed to the the bed section. After some debate over a toddler bed or a twin size bed, we went with a toddler bed. Olivia seemed most comfortable with the smaller beds and we wanted to make the transition as painless as possible. We tried out a few beds and went with this cute little iron bed.
Beyond that, we didn't do anything. It took a few nights (with Tom laying with her off and on), but now Olivia sleeps in her big girl bed. She has only fallen out once and I think she loves the independence that it has brought her. There is no cute bedding or anything like that. I had read that you should let them pick out the bedding and maybe if she had been older that would have been important. She honestly didn't care, so we just used bedding we already had. I stressed about the whole thing more than I should have. Olivia has always been a go with the flow kid. New things and changes are no big deal to her and it was the same with her big girl bed, It's Mila that will freak when the time comes. Maybe she will stay in her crib longer than 21 months.
I wish I had more advice. I asked for advice from everyone and everywhere before I made the decision, but I think you know your child best. What worked for us might not work for you (or your second child, ha!), but I love knowing how other people make transitions in their lives.
And because I haven't shared the girls' rooms, here's a quick look at Olivia's. We recently made some decisions that will hopefully be having us selling this house soon, so the decorating has stopped. This is her room partly decorated and now, it will stay that way. :)