Hi @J13C85, we were on the Regal last January and I was SO impressed with the Concierge Lounge and their ability/goal to solve all of our issues. We were a party of 12 with no pre-reserved dining table/time. The lounge concierge, Georgia, took care of the booking, and less than an hour later we had a reserved table for 12 waiting for us in the dining room, booked at the same time every night. We had a couple more requests that she seemed to resolve effortlessly, and she encouraged us to bring all of our questions/issues directly to her rather than guest services. She was BRILLIANT!
Not sure about the upgrade to premier over plus... Seems I read somewhere on the site - maybe check the chat feature?
Best of luck and have a great cruise!!