So, for you Princess Cruise veterans, what keeps you going back to Princess? I'm genuinely keen to know.
Interesting question, and honestly, it's hard to answer, part of it is going to sound all to common to anyone in the hospitality industry and part of it is going to sound strange*.
For us, there is a comfort level, we have been on many lines covering all the price brackets, as you hint at, when it comes to the mass market lines, it's like the hotel industry, little things set each brand apart, the first time we sailed on HAL I really didn't like it, the food was amazingly bad, the crew average at best, the next time was the complete opposite.
Carnival was great, good value for money, good food (their steakhouse is still a bargain) but over the last couple of years the cost cutting has just become more and more evident, the final straw was the movie to the American menu, the food was okay (some dishes were amazing, some terrible), but a silly thing like taking away the table clothes meant that on a moving, vibrating ship, we had glasses rattling, plates sliding (including a whole 8 top table losing everything when we hit a nasty wave), spilled drinks flowing across tables. Yes it's a small thing in the grand scheme of things, but it made a huge difference to us.
Princess, we have never had these issues with them, any time we step onboard there is a comfort** feeling, the staff are always friendly, the food is good, it hits the sweet spot for us when it comes to the party time (Carnival) and the sun has set, time for bed crowd (HAL) . They have the consistence thing nailed down, it doesn't matter what ship you are one, where you are sailing, it will be the "Princess" experience.
Certainly there are lines that are better, but IMHO, bang for the buck, they are hard to beat.
*My first Princess cruise was in Oct 2001 on the Sun Princess, Sabatini's served an amazing lasagna...I am a lasagna freak, I have searched in vain on every Princess ship, but nothing has equaled that first lasagna....Not going to stop me from trying.
The one big negative until late 2015 was the beds, I think Princess managed to buy all the mattress from the former Iraqi prison system, they were amazingly bad, to the point where we would stop at Walmart on the way to the ship and pick up a foam topper to put on top of it, then gift it to the room steward (we actually checked with them before we left it). However, Princess switched over to the same mattress Carnival uses, they are good, not Westin good, but good.
So in brief, good food, good crew, enough fun, but not to much...Oh I forgot, the C deck on the Grand class, these are regular balcony cabins one deck above the mini suites, the balcony acts as the roof to the mini suite, so you have a balcony 2 1/2 times the size of the regular balcony, great place to hang out with friends and have a glass of wine before dinner.