I've just made the swap to non run flats on 17" S-lites.
The tyres i chose were 215/40/17 Falken ZE512. (So far so good!)
Tyres at mytyres.co.uk: car tyres, 4x4 tyres and van tyres at low prices is a good start. You can enter your required size and it will list the available tyres. Once you have chosen a tyre, enter your postcode and it provides a list of fitters in your area.
Might be worth giving them a ring first to see if they're ok with taking run flats off though. I do not recommend using Wilco Motosave. I think they used a hammer and chisel to get my tyres off with the mess they made of my alloys. Anyway, that's another story.
The main advantage of non run flats for me is the cost. It cost me £260 for 4, opposed to over £700 for a set of run flats. The obvious benefits of run flats are safety and convenience if you happen to get a puncture. There's a good few threads on here discussing the pros and cons so have a browse.