Great news! I hope you like Grandeur. It'll be about as 'new' as it can get for your cruise.
What is nice is how RCI has announced they are committed to staying in Baltimore. I really like Baltimore as an embarkation port. BWI, no so much.
Celebrity Elite members get Diamond status so look for that printed on your cruise card and the little "D" logo on your Set Sail pass when the time comes to print it. Grandeur has one of the new dedicated Diamond lounges - or it will have once they finish up the fire repairs this week.