Hi J and S, the Emerald is indeed a LOT larger than the Sea. I loved the Emerald, she is beautiful. The Sanctuary was great. We ate in both Sabatini's and the Crown Grill (the extra fee restaurants) and they were both superb. I liked the Crown Grill better than Sabatini's because there wasn't so much food. The Black and Blue onion soup was fantastic. I still prefer the Sea Princess because she's a perfect fit for me. However, if you want to try a larger ship, the Emerald is a great one to try.
Here are some pictures, if you'd like to look. 20 vs. 14 days, I'd opt for the 20, even though I love the Sea Princess, I love cruising more