[Note: Both sets of caps feature the closing and opening of Frodo's eyes. When I quickly flick the sets of caps backwards and forwards, it makes it look as though Frodo is batting his eyes. He's seems quite endearingly saucy. If I knew how to make a gif, I would definitely make these caps into gifs.]
The first set shows a genuinely, un-self-consciously happy Frodo. He's a bit shiny-faced, as if he has become a bit giddy from the conviviality, good wine, and plenty of food, not to mention the burning lanterns overhead.
I think he is melting lovely in this little sequence. More than any other bookend shots, this set is so unreservedly, light-heartedly happy, I think it provides the strongest possible contrast to the Frodo we see after the four companions return to Hobbiton in RotK.
Farewell Speech, reaction shot #1:
In the second reaction shot, Frodo's facial expression simply makes me giggle. He looks like he's a little tipsy; his closed-mouth smile is nearly a smirk as he listens to Bilbo's remarks -- threaded as they are with double meaning. (Those two do like their little private jokes.) This sequence would make a hilarious "eyelash-batting" gif.
Farewell Speech, reaction shot #2:
Click HERE for table of Frodo and Elijah Wood Screencaps.