Originally Posted by catandmouse

Definitely worth going to the lounges. They are excellent. There's not a huge choice of food and the coffee isn't great, but lounges are spacious and comfortable. Normally you will be doing a T4S to T4S transfer (non-Schengen to non-Schengen) which is great as it avoids the main T4. You just have to go through a security check and I've never seen any lines at the T4S security check.
As the previous poster said, look for the VIP lounges. The Iberia lounge is not easy to find - it's just behind Starbucks in the centre of the terminal.