We really enjoyed our stay at Hotel Corallo. We came out of season (end of September) so Riccione and the hotel were both very quiet. We got upgraded to a suite, which was lovely with a balcony looking over the sea. Unfortunately the pool was too cold to use but looked nice. Breakfast every day was lovely. We didn't try dinner as we felt 35 euros per person for a buffet excluding drinks was very steep. We paid to use the spa one afternoon (24 euros for 3 hours). The sauna, steam room etc are nice, but the main spa pool was too cold and therefore not very relaxing.
Overall, we really enjoyed our stay and would recommend it. Some hotels in Riccione looked very ropey, and this wasn't one of them!