UPDATE:
I think this is harder than I thought it would be. Right off the bat I liked the dark pink better, just because it is fun and unexpected. The light pink is a Pottery Barn Kids color by Benjamin Moore. But I don't want the room to look Pottery Barn-y (Barney?) I do like the pros of the light: easier to paint over, flows with the other colors in the house, and once all 4 walls are pink, that will be a LOT of pink. It's hard for me to escape the $45 we could use towards other things in the room - there are lots of other things we want to paint (including 2 bookshelves, I'll be asking your opinion later for that one, I can go overboard with color or being too coordinated) and things we want to do to "finish" the room, and $45 could buy some fun stuff on my list.
The actual inhabitants of the room are split: Kate likes the light one, Nancy the dark. The problem with the above/below chair rail thing is that the chair rails is white, the bunks are cream. That drives me crazy, and I feel like with 2 pinks and then white rails and a cream bed....well, that's more than I can handle. Any suggestions for that railing? Oh, and those pink pillows on the beds? Horrible photo; the small pillow in front is actually almost exactly the same as the dark pink on the wall. The large pillow is just a sheet, we'll buy shams after we decide on the wall color. So don't let that sway you, either.
Lemme just say, I have LOVED the opinions. I hate making decisions like this, wish I could be breezy about stuff but I often treat simple things like this as a do-or-die situation, and have really enjoyed hearing which you like and why you like it. Wish we could have all done it over coffee and dessert!!

Without crazy bright spotlight, and I decided to make the beds.

Crazy bright spotlight.
We are in the process of finishing up the girls room this winter. Our task this week: Choose a paint color. The dark one on top is "Margaret Ellen" pink, or a mis-tinted, returned color that was $5 for a gallon. The lighter on is Pink Begonia. Try not to let the $45 we would save by using the dark pink sway your opinion, I want you to tell me which you prefer and why.
I never in my wildest dreams thought I would paint my daughters' room pink.