I think the question about Blu could be better answered by the Restaurant manager. I would assume that food would be made to order vs the precooked dishes that are served in the Main Dining room.
The main dining room is beautiful, so I would have to say it would be favored over Blu because of the extra cost if a table is available.
The food is pretty good in both restaurants.
I am Elite on a few cruise lines, I find that some of the amenities are standard issue in Aqua Class.
I have to recommend Princess for the perks, the unlimited Dry Cleaning and laundry is a big deal, even with Princess ships providing laundry facilities with irons.
Celebrity does not even have laundry facilities and Elite members only get a single item Dry Cleaned and a small bag of laundry, what a joke if your working out in the gym daily or traveling over seas on an extended cruise.