We chose the Seaside first based on cost. We've been to E. Caribbean many times, and Hubs is getting over medical problems, so we knew we would primarily stay on the ship.
Embakation was a snap because he was using a walker, so they offered him a wheelchair, which we gratefully accepted. We also had an accessible inside cabin, which was great. Lots and lots of room and large equipped bathroom. The ship was absolutely beautiful and never felt crowded, even with 5,000 passengers. What we especially liked were the many places to sit and gaze outside and listen to music or people-watch. We had the Fantastica experience which allowed us to choose our dining time, but for medical reasons we chose early dining. We had a very nice table for 2 but in a line of 5 tables, so you actually had 8 to 10 persons to converse with at times.
We found the food to be good and adequate, not great, but certainly good enough for us to be pleased. Yes, portions are a little smaller, but you can order more than one from each course. Dessert is ordered when you order your main meal. The buffet on Deck 8 was also good, but not great. As many have already said, lots of repeats every day, but the salads and soups were quite good, as well as very tasty pizza available almost round the clock, We are black card, so we chose Butcher's Cut for our one included special dinner, and it was wonderful! What a treat! The filet mignon was melt in your mouth, and Hubs had the rack of lamb, which he enjoyed, as well.
We had an accessible inside Fantastica cabin on Deck 14. We were very close to elevators, but had a quiet area. The cabin was very large and had a super large bathroom. Our cabin attendant was very unobtrusive but kept the cabin clean and did his job.