While we didn't get to play Portsalon, when we were in Ireland this passed summer we played 36 holes at both Rosapenna and Ballyliffin... both of which were tremendously worthwhile. If you have enough time and want to screw around with the late nights, you can even try to play the VERY COOL looking pitch-and-putt course right at Rosapenna... it's literally a dunes/links style course but with 40-80 yard holes. It was very cool looking, though closed when we were there.
Rosapenna's Sand Hills really surprised me... some great holes. A very nice setting and kept me happy all day even with the constant rainfall we played through.
Rosapenna's Old Tom Morris Links was very cool as well... as the Golf Pro at Portmarnock (Old) told us "The first 10 holes have what I believe are the best fairways in the world. Hard, Crusty, Crisp. The way golf was meant to be played." Agreeable to his statement, the first 10 holes are definitely the strong point of the course, though the back-nine doesn't falter. 18 was a particularly fun hole, crossing a road - this is especially true for us as the match between me/brad vs. my dad/family friend was all square on 18 and Brad tried to bomb a drive over the road, narrowly missing a car that was speeding through (haha).
Ballyliffin's Glashedy would be the one of these four that I would not play if you wanted to play Portsalon. It was still a great golf course, but my personal least favorite of the bunch. There are some wonderful holes and a very pretty setting, but in the similar style, I would chose Sand Hills over this course. Specifically the downhill par 3 7th was VERY out of place... it plays off the top of a 100 foot dune, and with the wind, it can almost be a four-five club change while dealing with a massive pond.
Ballyliffin's Old is the best example of rumpled fairways I have ever played (Haven't been to Scotland). As I've said in a previous thread, #1, #4, #10 all present EXCELLENT examples of this. This is a very fun course, and in my opinion, better than the Old Tom Morris Links at Rosapenna, as the two are similar style and this course lacks some of the oddities and quirks that bring down the Morris course.
Sorry I cannot report on Portsalon.
For a sample Ireland trip, this is what we did this past summer:
Fly overnight Wednesday to Thursday into Dublin.
Thursday Afternoon: Play The Island Club after some morning rest. (We didn't get to do this, due to plane mishaps.)
Friday: Drive down to European Club and play, then Drive back to Dublin. (Though that is a lot of driving)
Saturday: Play Portmarnock Hotel Links (We stayed at the hotel) in the morning, then drive down to Baltray and play County Louth in the afternoon; Drive back at night. (Lot of driving again)
Sunday: Play Portmarnock Old in the morning, Drive up to Rosapenna afterwards (A long drive, but very doable with plenty of time)
Monday: Play Both Courses at Rosapenna (We did Sand Hills in the morning, Old Tom Morris in the afternoon)
Tuesday: Drive to Ballyliffin in the morning, play Glashedy in the morning, then play the Old Links. Drive to Bushmills at night. (Very doable drive, not too long)
Wednesday: Play Royal Portrush Dunlace in the morning, play the Valley Course in the afternoon then drive to Newcastle at night (We skipped out on the Valley to get driving earlier... it is doable to play the Valley then drive; part of this was due to the fact that my dad's friend who was with us was slightly Golfed-out... not as hardcore as some of us
)
Thursday: Play Royal County Down in the morning, drive to and play Ardglass in the afternoon. (We didn't get to play Ardglass due to the fact that it was raining VERY hard and the wind was blowing 40 mph when we finished RCD... no starting an 18 hole round in that.) Drive back to Dublin in the evening.
Friday: Head home in the AM.
It was a solid trip, and though it had a lot of driving, all of the driving is worth it to experience the courses listed. I wouldn't have skipped any of those, though I hear Ardglass isn't in the same caliber as ANY of the others. It would serve as a nice break though, as I also hear it is easier than others.
Enjoy your trip! Hope this was helpful.