Henry Clay ran for President three times--the third time he lost very narrowly and would have won the election if a third party candidate had not tipped New York into the Democratic column by draining off some votes that would have gone to Clay. William Jennings Bryan was the Democratic nominee three times, and 16 years after his third try the Democrats put his brother on the ticket as their VP candidate (in the election in which the Democrats got their lowest percentage of the vote ever, if you exclude the four-way race in 1860 when there were two Democrats running).
More recently, Thomas Dewey was nominated again in 1948 after losing in 1944, and Adlai Stevenson was nominated again in 1956 after losing in 1952. Hubert Humphrey was one of the primary candidates in 1976 after losing in 1968. George Wallace ran again in 1972 after losing as a third party candidate in 1968 (it was in 1972 that he was shot). H. Ross Perot, of course, ran again in 1996 after running in 1992. Ronald Reagan ran unsuccessfully twice before becoming the nominee in 1980. Gore ran in 1988 before being the Democratic nominee in 2000. McCain ran first in 2000 and of course Romney ran in 2008. I think Dole was an also-ran once before he was the nominee.
I disagree with you about Ryan, though. He's a smart and likeable guy, but I don't think he's well suited for a White House run -- at least not yet. House members rarely make good presidential candidates, and in that respect he'd do well to run for the governor's office in Wisconsin before launching a presidential bid.
In retrospect, he probably wasn't a very good VP selection by the Romney camp. He didn't even bring his own state into the Republican column, and the GOP probably would have done better to nominate someone who appealed to a wider demographic group. Ironically, the VP position is such a useless spot that Ryan's talents probably would have been wasted -- and as the chairman of the House budget committee he was probably the only guy in the GOP on Tuesday who woke up on Wednesday morning in a better position than he would have been if he had "won."