Sometimes I wonder about how poetic and beautiful a language can be. What I've known though is that romance languages usually take the first place because of their poetically meaningful and nice sounding words. My favorite words in spanish would be these:
1) Gallardía - gallantry - When someone is courteous and his/her acts show courage and in general, an elegant way of acting. No wonder why there is a luxury Italian car referenced as "Gallardo".
2) Efímero - ephemeral. This word does have an english equivalent, however, it seems to be even more poetic in Spanish because it's mostly used in literary works.
3) Ensueño - dream-like. It's used mainly as a very positive expression where you talk about something you dream of but is quite difficult to achieve. Nonetheless every time you dream about it, that thing is pleasurable an "ensueño". It's also used to describe something that is beautiful and is found in Spanish expressions such as "fiesta de ensueño, boda de ensueño, casa de ensueño" etc...
4) Fantasmagoria - phantasmagoria. This word does have a similar equivalent in English both in meaning and sound. In Spanish though the "F" and "go" sound much stronger and adds even more personality to it.
5) Algarroba - Carob - while the real thing looks and smells quite funny its sound makes this a unique word. It has this characteristic double "rr" sound that is so difficult for us english speakers to pronounce and adds up a little flair to it.
If you happen to have more beautiful meaning or sounding Spanish words please add them! I guess any romance language word would be ok as well.