which would be more useful for someone traveling through China,
and which is easier to learn.

Mandarin IS the standardised and official language for all Chinese, unless they live in other countries which deprive them of a chance to learn the Chinese language.

Cantonese is a dialect used primarily by the people in Guangzhou, China. Of course, in many parts of asia like Malaysia, Singapore and Hong Kong (now part of China), there're quite a number of dialect speakers. But stick to speaking Mandarin because it'll come in very handy more than Cantonese. Many Cantonese speakers are also struggling to speak good Mandarin.

If you can speak Mandarin, learning Cantonese will be a breeze. The Cantonese sounds will just come intuitively as you watch Cantonese variety shows or listen to songs. I did just that and even learnt 3 other Chinese dialects!

FIRST..... determine WHICH DIALECT.... is spoken were YOU will Visit...!

Learn BOTH.... as most Chinese Know BOTH!

Thanks, RR

Mandarin for both. Mandarin has far more speakers than any other dialect given the fact that it's the offical dialect of mainland China. But even in places like Hong Kong where Cantonese is official, Mandarin is starting to gain some steam.
Plus Mandarin is a bit easier than Cantonese. There are 4 different tones that a person has to learn for Mandarin in comparison to 9 for Cantonese.
I'd bet my money on Mandarin all the way.

Definetely Mandarin. My girlfriend is from China and speaks Mandarin and she says that is the most widely spoken. Each region has it's own language, but they all speak both Cantonese and Mandarin, mainly one more than the other.

Mandarin.
It's like in the top 10 most spoken languages in the world. I don't think cantonese is.

Mandarin is the national language. They are both equally hard to learn.

Traveling through China? You should learn the written language lol.

Most people know Mandarin. It's actually difficult to survive in Hong Kong area with just Mandarin though...So many of them are stubborn to use Cantonese, or many of them don't even know Mandarin. The younger generation I say knows Mandarin in that area though, through education. But definitely Mandarin...the sounds are easier to make I think. There's only so many you can make anyways.

Good luck..

Surely Mandarin. Virtually everyone in China knows Mandarin, even if it's not their mother tongue (it's the education language all over China, and you learn it from your first year in school), whereas almost nobody outside South China knows Cantonese.

In the Northern half, almost everyone have Mandarin as their mother tongue. In the South, on the other hand, they speak many different dialects (Cantonese, Shanghai, Fujian, Hunan and so on), and they usually can't understand each other's dialect, so also in the South they use Mandarin when they talk to people from other places.

The written language is more or less the same in all Chinese dialects.