In Spain there are several trains which could be an interesting way to explore Spain.
Here are the websites which will have up to date information on prices, schedules etc.

Transcantábrico Clásico train:
The Transcantábrico tours northern Spain from Santiago de Compostela to Leon, and back again. A Luxury Train with  accommodation which is a mix of the classic train hall and ensuite modern salons with hydro-sauna,and five-star amenities. There are a total of 28 rooms on the train.

Transcantábrico Gran Lujo
Travels the north of Spain from San Sebastian to Santiago de Compostela vice versa. The train is an All-Suite version of the Clasico with only 14 suites on board and all the amenities you would expect in a 5 star hotel. The rooms have a sleeping area and a sitting area and of course they are ensuite with toilet and hydro sauna (high pressure showers).

Tren Al Andalus
The train Al Andalus is said to be the luxury palace on wheels.

El Expreso de la Robla
El Expreso de La Robla offers two distinct routes, one in spring and autumn, Castilla y Leon and the other in summer along the Cantabrian Coast.