Recently someone on Tripadvisor reviewed the Delfins and brought up the issue of two twin beds. Management responded that they do indeed provide a king top mattress upon request. Now I may be the odd one out, but the two twins side by side is just fine by me. When we were in Iceland this past summer, our place had the side by side twin bed arrangement. I slept wonderfully! Without sounding like I am husband bashing(okay, I sort of am), I didn't have to deal with him spooling the sheets off of me, the Jimmy Hand or flailing legs while he was sleeping. Then again, I don't like to cuddle when sleeping and need my space, or as my husband calls it "The DMZ". Perhaps too much information, but just my 2 cents
The only drawback to twin beds in the rooms is the prospect and potential of more little children staying at the resort. Terrifying!