Matthew, our group was comprised of two foursomes, all from the Philly area. We played RCD on Monday, July 21 (tee time 3:18) andTuesday, July 22 (tee time 10:06). Mike, there are 27 holes at Portmarnoch. The "old" couse is red and blue (played in that order). The yellow course looks quite nice. It is shorter and by reputation easier. It is the members' nine when the course is overrun with Yanks. We heard very good things about Castlerock and Ardglass, although most said not in the same class as Portrush, Port Stewart and, of course, RCD. I also heard great things about Ballyliffin, but it was too out of the way for us. I wouldn't miss Baltray, a great course to play when you are motoring from Dublin airport to points north.
BTW, for whaterver it's worth, I have pasted below the top 30 of the Golf Digest 2014 Ireland Golf Rankings, with a link below that for the whole article. As you can see, Portmarnoch is ranked #1 over RCD, perhaps for the first time (?).
Golf Digest Volvo Top 100 Ranked Golf Courses In Ireland 2014
1 Portmarnock Position: up 1
2 Royal County Down Position: down 1
3 Royal Portrush (Dunluce) Position: same
4 Waterville Position: same
5 Lahinch (Old) Position: same
6 Ballybunion (Old) Position: same
7 Tralee Position: up 1
8 Co Louth (Baltray) Position: up 1
9 The European Club Position: down 2
10 Adare Manor Position: Same
11 Ballyliffin Glashedy Links Position: up 1
12 Co Sligo (Rosses Point) Position: down 1
13 Enniscrone Position: Same
14 The Island Position: Same
15 Mount Juliet Position: Up 1
16 Carne Golf Links (Belmullet) Position: Up 4
17 Portstewart (Strand) Position: Down 2
18 Old Head Golf Links Position: Up 4
19 Killeen Castle Position: Down 2
20 Donegal (Murvagh Links) Position: Down 2
21 Ballyliffin Old Links Position: Same
22 Rosapenna (Sandy Hills) Position: Up 6
23 K Club (Palmer) Position: Down 4
24 Doonbeg Links Position: Up 2
25 Portsalon Position: Same
26 Portmarnock Links Position: Down 3
27 The Royal Dublin Position: Down 3
28 Lough Erne Position: Up 1
29 Carlow Position: Down 2
30 Dooks Position: Up 2
http://www.irishgolfdesk.com/news-files/2013/11/25/golf-digest-ireland-top-100-ranking-2014.html