I've booked several cruises with www.vacationstogo.com, and have been happy with the results. They don't do much in the way of hand-holding, but the two times I've had issues that needed to be corrected, they got the job done quickly and easily. I find their web site particularly easy to use.

I also don't care for the assigned dining times/tables either, and usually just eat from the buffets and other food opportunities elsewhere on the ship. Works better for me. I think it is Celebrity that has a "Spa Dining" area where meals are lighter and healthier. Still lovely presentation of the plates, but lower calorie simple things. NCL may well have something similar if that would appeal to you.