Hi there,
you could try Hostal Rey Don Jaime on Calle Jaime in Barcelona, the location is fantastic.
RE the double room thing..the rates given are almost always per room , not per person.
I find it is always worth asking for a "cama matrimonio" (!!!) or "una cama grande" to ensure the double bed.
The location of this hostal allows you to explore the area of La Ribera, Born and the port as well as barrio gotico without being right on the ramblas.
Hope you have a lovely time