It all depends on circumstances as to what your weekend toy can be.
I bought my GTI new in May 2006. It's just turned 7,000 miles and only comes out (some) dry weekends as I have a company car for a daily driver. I enjoy driving the GTI at weekends and also enjoy detailing it. The thing is, I have a wife and 2 girls (4 & 7 year olds so have to have a car which has a bit of boot space for days out as well as a proper back seat for child seats. 3 doors is fine though. My father in law is in a similar situation and drives an ed30. He has a boat and needs boot space for carrying stuff.
For myself, I would like to have some sort of Porsche but I need some practicality. I have to agree that for £20k to £30k, VW and Audi have some interesting options (Rocco, S3, gti & Golf R, TT).
You need to spend a lot more money to get a decent BMW in my opinion and then you still have 'another BMW'. My company car is a 3 series albeit a poverty spec one. It's a good mile muncher but will never put a smile on my face like the GTI
Nowt wrong with changing a car you hardly use. I would do the same if I could afford it and it would be either a Scirocco R, S3 or R Golf