Well it depends on the place and topics that you use, but yes they can generate some good traffic and make decent money.
You will want to write about things that people might search for who are planning to visit, so anything too specific or on a topic that only locals would know to look for should kind of be avoided.
For example, a post entitled: "entertainment in San Jose" could do well, but a post that used the specific name of your favorite bar or venue in San Jose instead of a generalized topic will probably have much less luck.
Here is what you should do:
#1: Go to adwords.com and create an account or login with a google account
#2: Under the reporting and tools tab go to the keyword tool
#3: type in the name of the location you plan to write about and see what people search most often for that area, then try writing some articles targeting those words.
Google's keyword tool might be a bit confusing at first if you've never used it before
CPC is the average amount Google will pay you for an ad click on the topic of the keyword, so look for keywords that have a good CPC and a large amount of searches, either locally or globally.
You can also put the search into Google and take a look at the websites that currently rank on the top to see if you could realistically compete or even beat them. Use SEO for Firefox to check the Pagerank and other factors of websites.
You can also use adjectives like "affordable, good, best, cheap, etc." to attach to the beginning or end of key terms that might be too difficult to rank for.
Hotels in London will undoubtedly be very difficult to even appear in a Google listing for, but "popular hotels in london" or "hotels near x landmark" might generate you some solid traffic and income