Betit,
As far as the Gold Cup goes, it has been a very strange one so far, with the surprises we have seen, like Guadaloupe beating Canada, Haiti drawing Costa Rica, Costa Rica downright losing to Canada, Mexico going down to Honduras, Panama beating Honduras and so on....in reality the only team that has proven their status is the US and to a certain extent as their 1-0 over Guatemala was very difficult.
Today its the US against El Salvador, a much inferior team on paper. If you can find a 3 like I did at a book I would strongly recommend taking the under. The US should win this but their motivation might be a tad iffy because they are already thru to the next round, then again, who isnt (8 of 12 qualify) Nonetheless they will want to win this game to assure first place.
If you find a price youre comfortable laying, they should win it.
Guatemala Trinidad is a battle between two teams with little to offer, two teams with very limited skills, as are most teams in Concacaf. Usually matches between teams of similar rank in the concacaf mean under. Guatemala is the better team between em both and should feel at home in this one as there plenty of Guats in the USA.
Guatemala 1-0
USA 2-0
would be my two guesses.