Congratulations UEFA, as well as being unable to foresee the visa issues with holding the final in Russia, they didn't realise an artificial pitch may not be the best for the occasion either and it may come back to bite them in the arse:
BBC SPORT | Football | Moscow pitch causes final concern
As for the United bench, I'd personally take:
Kuszczak, Silvestre, Fletcher, Anderson, Park, Tevez, Saha.
I think that's the best choice because each player would provide something completely different from every other player on the bench, you could argue O'Shea instead of either Silvestre or Fletcher but I think Silvestre is better in defence and Fletch is better in midfield, or Nani instead of Park but Park is in better form and has earned his spot in the squad, maybe even perhaps the starting line-up.