I have to second the recommendation of Lustau East India Solera. However, depending upon the flavoring you desire, you may wish to consider using casks that have previously held sherry, rather than adding sherry to your spirits. This requires careful cask selection and a nearly total trust in your cask supplier.

Without attempting to highjack your thread, another interesting offering from Spain is an excellent brandy. . . . Manso and Contreras Brandy de Jerez. Like Lustau East India sherry, it is aged in the solera fashion. I don't, for a moment, pretend to know what that means, but whatever it is, I have come to appreciate what it does for darker color, complexity of flavors, and an unrivaled finish in both sherries and brandies.