Isn’t Kirkiston an Old Tom track? Or Colt. Somebody famous. @AndyDowney is a member there I think.
Newcastle is a dump but the pubs / pub (can’t remember if there is more than one) down in Dundrum are a bit more low key. Downpatrick is close too, especially post the Ardglass round. You can go see where St Patrick is actually buried.
There are a few nice restaurants around the Strangford Lough area. So, Strangford, Portaferry, Whiterock. If you fancy a drive take the ferry over and drive to Donaghadee, where Grace Neil’s is the oldest pub in Ireland (can be a tourist trap though). Going the other way, Rostevor is a nice town.
But I’d agree that your best bet is heading into Belfast, which is probably the best night out in Ireland if you want to get into a bit of trouble. It’s only about 45 mins from RCD. The Cathedral Quarter is where you want to be but Botanic has a more student vibe if that’s your bag. Some great restaurants in the City Centre. Start with cocktails in the Merchant Hotel and just follow the noise from there.
That being said, once you’ve played at RCD you want to hang about the clubhouse to eat. Some great characters in there. Then head to the spa at the hotel. You can sit in the pool there with an infinity edge window that looks up at the mountains. You won’t want to leave.