The Royal Duchy Hotel was located right off Gyllyngvase Beach and was one of the nicest hotels I’ve stayed in. I had a single room that offered a Nespresso machine, heated towel rack and radiator (good for laundry) and other amenities. The hotel also had a fitness room and swimming pool. Breakfast was included and was delicious and the price averaged around £75/night (I was there the end of March, and double rooms were probably more). Best of all, there was a view of the sea from my window.
I especially enjoyed the large lounge area on the ground floor, which opened out to a patio sitting right above the coast. You could have a drink or order a meal here and just watch the ocean. There was a formal restaurant as well, but I liked the lounge and ate here most nights, as the food was delicious. There was also plenty of parking, and it was a short walk down to the beach. Pendennis Castle was about a mile away, and the harbor was a quick 10 minute walk (also the National Maritime Museum). It was also close to the main road so easy to get out of town on day trips relatively quickly. I highly recommend this hotel and would love to stay here again.
Edit to fix typo.