The Grotto pool is on par with Stormalong Bay. In fact, we liked the Grotto pool better because it was less crowded. We had no problems finding two lounge chairs there during the afternoon. We were doing our laundry at the Dolphin and sat out for a couple of hours. There were plenty of chairs around and I didn't see any "chair saving" at all.
One word of advice - don't sit behind the waterfall. We tried it, thinking it would be quaint. It's LOUD!