Most logical foreign language to learn. (sales, amusement park, hotel)

[Cornwell]

haha i started researching esperanto cuz of your post and gotta say its nifty.

[oc2eire]

Mandarin, Spanish, and French.
Done!

[Chinolala]

Madarin, Russian and Spanish

[Quadcore]

I would recommend Chinese(Mandarin). Because Chinese is a language that is really different from English. There's no such thing like alphabet in Chinese language. It's totally another kind of language. You'll finally find that you are learning a new way of thinking.

[Crew Chief]

Originally Posted by lisak64

Madarin, Russian and Spanish

Spanish is rarely spoken outside of Spanish-speaking countries (except to Hispanics in the Estados Unidos...)

[mead]

My picks would either be Chinese or Spanish depending upon what your focus is on.

Remember that Spanish is a hell of a lot easier to learn than Chinese. You could study Chinese for years, do a year long exchange in China, and still only be somewhat fluent.

[jsfountain]

Got to go with Pig Latin. It's the new Mandarin.

sthay isway anway exampleway ofway Igpay Atinlay. Asway ouyay ancay eesay, itway isway illysay, utbay ortsay ofway unfay orfay ildrenchay.

It translates back into standard English as:

"This is an example of Pig Latin. As you can see, it is silly, but sort of fun for children."

[K-Luv]

Originally Posted by lndigo

Russian is a Slavic language. Chinese isn't too grammatically different from English, and I haven't found it too difficult (Although I'm only learning how to write simplified, what they use in mainland China, not traditional).

Mandarin is a from of spoken Chinese, and written Chinese is based off Mandarin.

If English is your native tongue then Mandarin will be more difficult to speak. Cantonese, if you are and English speaker, will be much easier to speak. Chinese is written in the same characters regardless if it is Mandarin, Cantonese, simplified, mainland-does not matter.

It all depends on where you want to focus on doing business. Spanish, Russian, and Chinese (either Mandarin or Cantonese) would all be benificial in the long run, but there is not point in learning Spanish if you are going to mainly deal with Europeans.

[lndigo]

Originally Posted by K-Luv

If English is your native tongue then Mandarin will be more difficult to speak. Cantonese, if you are and English speaker, will be much easier to speak. Chinese is written in the same characters regardless if it is Mandarin, Cantonese, simplified, mainland-does not matter.

Are you basing this off experience? Cantonese has nine different tones that are a must while speaking, while Mandarin only has one. Since written Chinese is based off Mandarin, it's much easier to learn Mandarin while learning written Chinese, whereas Chinese and Cantonese have different grammatical structures. Simplified Chinese is used in Mainland China, while Traditional Chinese is still used in Taiwan, Singapore, Hong Kong, and most everywhere else Chinese is use.

[Mississippienne]

Which area of the world are you planning to focus your interests? Keep in mind that there are very few truly international languages, languages that are spoken by many millions of people the world over and are important for business and society.

Mandarin isn't quite there yet, but is extremely important inside China.
Russian is important for Russia and the former USSR countries, and would give you a good basis for learning other Slavic languages, such as Serbian.
Arabic is of course important in the Middle East, and also studied by educated Muslims across the world.
Spanish is spoken across central and south America, some of the Carribean islands, and in Spain.
French USED to be THE international language, but lost a lot of clout over the past 150 years or so. Still spoken in France and parts of Africa. Not a bad second language to have by any means (it's my second tongue).

None of these are closely related to English. English is a Germanic language and it's cousins are German, Dutch, Swedish, Norwegian, Danish, and the other Scandinavian languages. The only distant cousins on this list are French, Spanish, and Russian (all Indo-European languages). Arabic and Mandarin would be a whole new world for an English-speaker.

Aside from this top tier, here's some second-tier languages that might be interesting. While not as widely spoken as the stalwarts such as Mandarin or Spanish, they're important in their own right.

Turkish would give you access to the fascinating culture of Turkey and also a springboard into the other Turkic languages. It also uses the Roman alphabet (ABC, etc.) so if you can't get the grasp of Mandarin or Arabic's writing systems, this would be a good choice.
Farsi, or Persian, is the language of Iran. It's also a distant cousin of English, being an Indo-European language.
Swahili is spoken across East Africa and is also written in the Roman alphabet, just like English.