With DD1, I knew her bio dad would not be involved so I gave her my last name. I figured if he wanted to be part of her life, he could go to the work to have it changed, and if I remarried and she wanted to be adopted, we could change it at that point.
Since my remarriage, she has not wanted to be adopted by DH, nor take on his name (she thinks it'll sound dumb with her name). We give her that choice, and her name is hers either way.
If dad's involved though, I think if he wants his child to have his name he should have that right. JMO
