Hello, one hotel I know of, though it was my brother in law who went there and had good words for it was the Hotel Prestana Dom Joao ll in Alvor. This is a 4* hotel with good activities if you want them, you can also use the facilities at near by hotel Delfim, it has 330 bedrooms on five floors so is a big hotel, one of its two pools are heated in the winter.
My brother in law told me they do a wonderful Gala Dinner here and at the time he went you also had free drinks with the Gala Dinner, you can find this hotel in the Portland Holidays Direct winter book, but like most places at this time of year it will not be cheap.

http://www.portlandholidays.co.uk

Dave.

Many thanks for your advice I will take a look at that hotel