I'm actually trying hard to remain unfamiliar with RyanAir . Seriously, they have what, a dozen destinations on the continent from SNN, with a single flight per day to each; good luck making a reasonable connection to an international flight. Also, you can't interline AA-FR so, provided you do get a reasonable connection, you have to claim bags, schlep through airport, check bags, and reclear security. Then you have to fly FR which, though I've not done it, sounds none too pleasant, and you end up in Beauvais or Hahn or Charleroi instead of Paris or Frankfurt or Brussels. Of course, if your AA flight is late, you're pretty much screwed since you've missed the one FR flight of the day, and vice versa on the return. Since I no longer travel quite as lightly on vacation as I once did, it's just not worth it for me, even to save several $100s.

On the other hand, BOS-DUB-XXX on AA/EI would be worth it even at a slight premium over the LHR connection because, well, you've got to connect somewhere and DUB seems like an easier place to do it; plus the "FC" upgrade, of course.

YMMV

Michael