If you disregard the two Playoff Bowl Games, the biggest intangible by far for this bowl season is simply which team want to win the most. Not counting the Playoff games and games that are not lined as of yet, I see 15 bowl games with lines of 3 1/2 points or less. A line of 3 1/2 points or less basically means that no one is sure what will happen. In those games, the teams that wants it the most normally prevails.
Other things to look for. In the Potato Bowl, Colorado State is listed as a 10 1/2 point favorite over Idaho, even though Idaho should have a big crowd advantage. What people may not realize is that Idaho was basically strong armed into going back to the FCS in 2018. This team that had a 1-24 S/U away record not only won 8 games, but won 3 away games. Two of their away losses came to the Washington teams, both of which are in bowls. Idaho had something to prove, and did so. 10 1/2 points seems to be a gift.
Home Field Advantage: New Mexico UCF, and Hawaii are playing on their home fields. Other teams like Troy, La. Lafayette, Idaho, North Texas, Temple, Texas A&M, Tennessee, and USC are playing games very close to home and should get big crowd turnouts. This can effect games, and also effect the lines for those games.