Hi,
My advice is to get over the "L" bias and look at the 17-55 EF-S IS. It has more reach than the 17-40 L, has equal IQ, constant f/2.8, and IS to boot (which will help with the night shooting).
My 17-55MM EF-S IS is my walk around lens and generally stays on my 30D 
Two drawbacks: it is EF-S and will not mount to a FF body, and it is not cheap. But you get what you pay for. I'll hold my 17-55MM EF-S IS copy up against any WA or mid-range "L" zoom lens.


. I would even be happy with a 17-70 f/4 L IS and would recon that would cost about £600
