Ranieri was the coach of Cagliari between 1988 and 1991, taking the Casteddu from Serie C to Serie A in three years, so its not wonder that they are also interested in bringing Ranieri to their side. Ranieri's contract expires this season with Sampdoria and his contract still hasn't been extended, which means he is most likely going to be a free agent in the summer.
Ranieri coached Valencia between 1997 and 1999, before he returned for a season in 2004-05, which didn't end too ceremoniously.
Peter Lim and company have already decided that Javi Gracia won't continue past this season and have been looking at possible replacements, with coaches like Diego Martinez and others also being looked at as possible replacements. For this team right now I think a coach like Claudio Ranieri just might work. He is known for building teams up and Valencia CF for the past 2 seasons have been at best a mid table club, so there is a lot of improvement that can be made.
Ranieri's age should be taken into consideration, he is 69 years old so one has ask how focused he will be on the task at hand and will he have the energy to implement his ideas and style at this age? I don't think 69 years of age is too old, but its getting there. I think if we can get him on a one year deal with an option for one more year would be great. He can start working his magic if he is able to and if he is successful the club can extend his contract with a build in option.