Just stayed at The Hotel Avenida which is situated right in the heart of the old town.
My wife and I have stayed there several times and thoroughly recommend it.
The staff are very friendly and will do anything to help. You can either book room only, B/B Half board or All Inclusive. We prefer H/B because you can either have lunch or dinner. Having lunch means you can eat out somewhere different every night. Bars and restaurants are so cheap in Benidorm.
The hotel is a small family run hotel, rooms are nicely decorated and sheets changed daily. Food is brilliant with a great choice at every sitting. You can help yourself as it is buffet style. For families there is entertainment every afternoon in the lounge with entertainment also in the evenings.
A roof top pool area includes a gym and a jacuzzi. It is just a few minutes walk to the beautiful Levante beach and just a quick taxi ride to the busy new town area.
The old town is very much still very pretty with a very Spanish feel.
In all this is one great hotel for couples.