vntourism.info This is one of my website, I optimized it for SEO, the alexa ranks is 1.6m now and have hundreds of visits everyday But it haven't got any pagerank, I don't know why. The same to web-vn.com , kinhtetre.net and every page of mine, althought kinhtetre.net have more than 300 visits/day What can I do to get a high pagerank for those?
Toolbar Pagerank that you are running after was a thing of the 90s and not so popular these days but any way it is a function of backlinks and not a function of traffic
To get higher Page Rank, you need to make your website popular (brading & viral marketing) and you should build relevant backlinks from high page rank site in your niche. These some great place to get backlinks: Facebook, twitter, video sites, web 2.0, articles, guest posts, blog comments, forum , directories and so on
As per my personal opinion Page rank doesn't matter if you getting good visits on your website. Pagerank is Google own algorithm to rank any webpage and general internet users who really wants to buy something from internet or wants to get information he'll doesn't matter if your website have PR or not. If user can get satisfied information or products from your website than nothing to worry..
Google has define so many factors for page rank and it will update after a long time, so keep patience and regular work for optimizing your website
Page Rank update around 3 month so work to get good and relevant link and hope you get PR on next updates.
To get high PR for your web pages, You need to concentrate on both traffic as well as link building for that particular page. Only link building will not matter that much as you think about that.