Received the same offer of a comped room, $75 freeplay and $25 FB credit from Aria that I received from MB

do they charge resort fees on comped rooms at either MB or Aria? If so, how much?
Any other fees I should expect to be charged while staying in a comped room?

Not sure how I got a players card number at Aria, but it is different than the one I have for MB.

They both charge resort fees, but I've found that MB normally doesn't charge them on comped rooms. I think Aria's was over $20/day.

I stayed at Aria last trip. 2 nite comp stay.

I grilled Check-in, and was told NO resort fee on comped room.

At check out, NO resort fee. Good!

As far as resort fees at MGM properties...

It really depends on who you talk to and sometimes how much you complain.

When I last stayed at Aria they did not charge me for one but who knows if they will try next time.

If they bother you about it just say, "I was told comped rooms are not charged a resort fee."

MB may be different. I won't stay there due to
a bad experience I had about 10 or so years ago.

Aria does not charge resort fee on comped rooms.
My host told me that MGM properties overall do not charge resort fee on comped rooms.
My last 4 stays have bee at Aria twice,MGM and Mirage.All comped rooms and no resort fees.

Aria and MB no resort fee on a comped room. That is the standard for all comped rooms as of 2 months ago. Best thing to do is call marketing and ask. If they say no just have them send you an email to confirm and note your reservation.