i know an inch doesnt make much difference but it doesnt change anything apart from looks
For a start fitting 17s has made your car sit around half an inch higher, assuming similar profile tyres. Straight away you need a drop of ~15mm just to get it back to factory ride height, even more if you don't have super-low-profile tyres.
P.S. what size tyres did & do you now have? (It's possible to work out the amount you need to compensate by if you have the sizes)
In here and some other threads I've noticed you're a bit undecided on height. I've seen 60, 45, 40 and 30mm mentioned by yourself I think. As well as pleasing the technical side of things (dampers, spring rates, suspension geometry etc) a bit better coilovers are also adjustable, meaning you can get the exact "drop" that you prefer. It's not a "spend £100 and hope you don't wish it was a tad lower/higher." Obviously you do pay for the convinience.
There are other reasons why 16" wheels are probably a much better choice, but they're all handling/tyre-life related when (fair enough) you're going for looks. Don't forget to take some before/after pics when you do get it lowered!