Thanks this has been a really useful thread - trying to solve the same issue since upgrading to 8.1 on my dell venue 8.
In addition something I think Microsoft need to look at based on my investigations:
-my router is dual 2.5 and 5 GHz, when turning off the 5ghz my wireless was completely fine on the venue - seems like the smart wireless confused the connection.
manually setting a dns entry is a great workaround but like you say it will have to change each time you move to a new connection.