@Zachary is correct that is what SeaWorld is focusing on. They aren't trying to get people to visit them over Disney/Universal for their. Instead they want to convince people that should spend one day of their vacations at SWO. They have also been borrowing heavily from BGW in trying to cater to locals as well as convince people to come visit.
This is essentially how I approach any family trip to Orlando, the first half day (arriving in Orlando area) is spent at SeaWorld with dinner there and the last day of our trip (departure from Orlando area) is spent at SeaWorld with lunch there; then we have a single full-day at SeaWorld/Aquatica mixed in with our remaining six days in Orlando, because 6 days straight at even the four Disney parks is too repetitive.
Glad to hear that SeaWorld is also approaching the same plan I have been using for years and catering to the "mix in a day or two" idea for a Disney-focused trip or Universal-focused trip; to me the mere mathematics of being an all-parks (platinum season pass holder) justified the book-ended visits alone. If somehow an all-parks dining plan, similar to Cedar Fair's, was implemented by SeaWorld, then the value proposition only increases and pushes me closer an even split of days at SeaWorld vs days at Disney/Universal.
Lastly, the lodging value of the "at Seaworld" properties is becoming more and more of an economics no-brainer as compared to on-site Disney or Universal mid and top tier lodging. Universal's built in Express Pass when staying at upper-tier property is extremely nice, but the economics of the on-going arms race of pricing for said upper-tier property is making the attractiveness of SeaWorld properties even more appealing as we can literally justify making an annual trip by staying off Disney or off Universal property instead of saving up for the "on-site" experience every few years.
