We have a jokey saying that Swansea, 50 miles from Cardiff, 50 mins on the train, is just a suburb of Cardiff. Newport is maybe 15 mins on the train from Cardiff. The way the train stations are situated and frequency of the trains makes it really easy to slip between them.
Personally at my age I fancy something a little rural, but with decent transport links, rather than the bigger cities, but I would imagine many young rugby players would be quite at home around Cardiff.
From a rugby pov I think Cardiff are more attractive long term, and generally playing for them will open up more local post career opportunities than the Dragons. I also think the Blues could do with some ballast, so WR is a great fit for them.