I wish they did R Design with the option of removing the "sports" suspension. I think quite a few people would have chosen that. I really like the R Design seats but I'm told the difference in ride due to the suspension is quite significant I'd I'd like to do all I can so as not to feel the potholes.
Wheels are again down to personal preference. I'm not a huge fan of diamond cut styles since as soon as they're damaged there's not much you can do to save them except go for a solid colour. The lacquer never seems to last on a refurbishment and it's more expensive to do. Having said that - the 20 inch wheels on the D5 on Piston Heads do look pretty cool
That seems quite a fair price for a car from a dealer. I've kind of got my heart set on a 2 litre 8 speed though for the economy and smoothness without too much drop in performance.
Your warranty and servicing, in my opinion, absolutely do add to the value and I'd have no problem paying a bit more - £300 maybe.