Thomas, To answer your first question, yes! There is nothing harder (for this moderate golfer) than the shot into a flat and unprotected seaside green.
To answer an earlier question on this thread, Harlech is constrained in almost all matters of rough control (not just the immediate semi etc), by the protocols of Natural Resources Wales: there is a very good and informative greenkeeping blog on the website at RStD by the excellent greenkeeper, Rhys Butler. NRW can also (as at Aberdovey) influence the placing of tees and other features, despite the club owning the freehold. Much more seriously, NRW also controls the overall drainage protocols for Morfa Harlech, and I am sure that GCA members will have seen some of the sharply critical comments on some other golf sites about the recurrent water at Harlech this year, in the bunkers and elsewhere. There is a medium-term issue here happy resolution of which is fundamental to the future health both of the course, and of the RStD club itself.
As an example (I think) of getting seaside rough 'right', just back from a couple of days in Norfolk. We played 36 holes of singles at Hunstanton yesterday and 36 at Brancaster today and the latter, in particular, still encourages width with pleasingly few opportunities for losing balls (unless wrestling with the various fences or the sea tangle). There is probably a bit more fairway shaping in the past, but the great thing about Brancaster remains that nobody involved has any aspirations for the club and course to be more than the supremely natural, endlessly interesting, member-friendly challenge that it is. Nothing is being 'tricked up' in the search for difficulty. Hunstanton (which I still place on a somewhat lower rung, overall, than RWNGC) was in perhaps the best 'day-to-day' condition of any course that I have seen this year, and the problematic rough (in Sean's terms) was in the wetter, lower-lying parts.