Hi
The 525 is in Los Alcazares. We are at the El Trampolin site and it takes us 20 mins by car. I don't know how far from El Trampolin to TH, another 20 mins? Have a look on Multimap or Google Maps.
The hotel does look lovely and has a nice bar but it is a bit pricey! I think it was 100 Euros per person per night when we had a look round. More of a boutique hotel.
I think the Hotel Costa Narejos is a very good hotel. It is at the other end of the pedestrian area going towards the beach and has an outside pool. About 34 Euros PP/PN.
Web Site www.hotelcostanarejos.com
I think hotels in Murcia City will be closer for you but LA is a nice place to stay, nice beach, good places to eat and a good base from which to explore.