Khulna has an ODI venue .... hopefully some new hotels etc will come up soon and become a test venue. The Rajshahi Divisional Stadium was refurbished few years ago for some A level matches and is pretty good actually. Even the Rajshahi University Stadium is great.
Also has air link and great road (only 4 hours from Dhaka these days) connections now. But the problem is the lack of good hotels in that area. Unless that happens - it would be difficult to have an ICC approved place. Sylhet would probably become one before Rajshahi.
hmm all of those cities are abosolutely stunning, I mean if you make hotels once overseas cricketers come and see our cities they would delighted, and think about all the tourism revenues !!!