Can't believe this is gonna be my first post. Congrats on the new baby!
No woodworking expert here, but a big fan. Heres the table I built for my son. Its a changing table for now, and will be a dresser when he gets older.
IMO , the only thing that need to be planned, is that the size must hold the pad ur gonna buy from the baby store. As for the height, I figure changing dipper is sort of like doing woodwork on ur bench. Consider your wife might be shorter than u, assumed, make it a couple inches shorter than ur bench.
Rest of it, is simply to build a box, a few drawers, doors, and whatever, surely with your favorate joinery.
My table may not be one of the pretty ones. But my wife liked it a lot. My son has been on it now for 6 month and no complaint as I can tell.
Finally, build it strong, so you add a zero to your babies weight, let it still hold. Can't realy stand with those shaky changing tables sold in the store.
Good luck building. pictures expected.