Although you may not have liked how it came about, I think you have gotten some really solid advice here. Advice that has the best interest of your family, Sadie, and any new fur-babies at heart. There are some unknowns in your future.
I hope beyond hope that when your baby arrives he/she is nothing but perfectly healthy and that your wife is gifted with the world's easiest birth experience EVER. But, sometimes that doesn't happen. Sometimes new mom's have complications that render them the newborns milk jug and precious little else for the first few months of the babies life, etc. Think of your family dealing with your wife recovering from an emergency c-section with a fussy baby that is having trouble feeding (not at all uncommon). Now imagine having to meet the demands of even the most awesomely behaved puppy in the world under that sort of stress. I'm not saying it cannot be done, but I'd suspect it would be rather hellish. And I would not wish that on you or your wife.
All in all, if you want to round out your family, you will. I would also recommend waiting a bit after the baby is born, give yourselves a chance to adjust to the new normal that life will be with the baby. After that, however long it may be, get your puppy.
You gravitated towards a newf the first time for a reason. I would consider a second for the same reasons, but the type of dog really doesn't matter. I wouldn't put a toy out to play with a newf I guess, but the next breed you go with should fit with your family well in regards to temperament, activity level, maintenance level and cost of care (we all know kidlets are freaking expensive, so it would be a consideration for most families I would imagine). In general newfs get along with just about every breed of dog on the face of the planet. I'd be more concerned about matching another dog (even another newf) to the temperament and personality of the one you already have. I'd also keep in mind that your newfie is a baby and likely has no idea her own size or strength...that would lead me towards a larger sized dog, but they certainly can be taught to play nicely with small dogs. Sulley is quite respectful of small dogs and it wasn't me that taught him that, but a few well placed nips from smaller dogs that did not appreciate being run over.
