I realize that reading the Hobbit and LOTR a dozen times or so does not make me an expert on literature or Tolkien any more than driving a car for 18 years makes me an expert driver, but here’s my take on Frodo’s role in LOTR:
The LOTR chronicles the events leading up to, and including, the destruction of the One Ring (set in motion by events in the Silmarillion). Frodo’s role in these events basically consists of being a delivery boy, er hobbit. Even then he fails in the end, as partly_warmer points out, as Gollum has to bite the damn thing off to get it from him. I realize that at this late stage of the book that Gollum is merely representing Frodo’s Dark Side™, but if he (Frodo) was truly behind the whole point of his “mission” he would have held on to the Ring all the way into the fires of Mount Doom to ensure its ultimate destruction. Instead he held back just as Isildur did and threatened to start the whole cycle again (keep ring, lose ring, find ring, destroy ring). Most heroes die in the end in your classic epic tale (I will be posting an OP in the near future to debate Gollum’s whole role in the story. Feel free to post your comments there.)
I feel that Tolkien shifts the story from Frodo and Sam (and Gollum) for such a long time to keep us from getting more bored than we already might be with the events at that point. To keep things exciting, yet chronological, he skips past a lot of the walking and stalking going on with the three Ringbearers and instead concentrates on Merry and Pippin’s near rape-fest with the orcs (I feel certain that orcs did not withhold their sexual desires nearly as much as Tolkien’s omissions would lead us to believe) and Aragorn/Strider, Legolas, and Gimli’s pursuit of M & P. I must point out here that I don’t believe for a second that two sheltered and inexperienced hobbits would have been able to make the journey to Mordor and Mount Doom on their own and can’t fathom Aragorn’s decision not to send at least one of the three remaining ex-Fellowship members to accompany them. Probably makes for a better story down the road is what Tolkien found out.
As for who the main protagonist is in LOTR, well, I feel that Gandalf, Frodo, Sam, and yes even Gollum could lay claim to that title. But realize that the One Ring is still the motive behind each character save Sam, and for this reason I award him as the character that “grows” the most during the story. If Gandalf had been smart, though, he could have simply put the Ring on a chain, given it to the Lord of the Eagles (who apparently has no problem with airspace rights over Mordor as IIRC rescues Frodo and Sam from impending doom, pun intended), who subsequently drops it in its birthplace and been over with the whole mess in the space of a few days. But who wants to read that?
As for an uninteresting Middle-Earth book that Tolkien wrote, that (for me) would be the Silmarillion. I made it about a third of the way through before I determined it was too much like an encyclopedia. A lot of names and dates and places but not a whole lot of adventure. I’ve been told that things pick up near the middle of the book but have never gotten around to finishing it. That said, I still hold the LOTR as one of the better books written in epic tale fashion, the likes of which have rarely been equalled since and recommend everybody give it a least one go. The debate as to whether Tolkien meticulously put his story together or cobbled it from ideas on bar napkins is irrelevant to me. I still like it.