You sound like an excellent nurse who loves challenges and learning. Very commendable. As a new grad, I would have love to have done that much variety.
That said, I hate to be the discouraging word here, but, babies are whole nother species. I don't think it's a good idea to "float to NICU sporadically". It's too hard to pick up subtle signs of sepsis, NEC, and other disasters if you don't have a really good grounding in this specialty. NICU is vastly different from adult nursing: normal VS, calculating dosages, and pathophysiology.
If you do decide to take this on, try to go there more than you go anywhere else. Get a copy of Merenstein and Gardner (look on Amazon
for it) find a good drug reference like Neofax, and study them. Wash your hands a lot!
I wish you the best. If you like this area of nursing, try to get a position that doesn't have you going all over the hospital, with an occassional visit to NICU.