I think it would be great to have a conference in Harrogate, UK. It's got the 3rd biggest conference/exhibition facilities in the country, it hosts the 2nd biggest toy fair in the world every year and the conference centre hosted the eurovision song contest back in the 80's.
It's got loads of really nice hotels, lots of night life, loads of shops and generally looks nice too. Easy to get to. In between London and Edinborough.
So if your looking for somewhere to host a PHP conference, go to Harrogate.