Julian Wright's a SF, and a pretty good one too. Between him Weems and Kleiza I'd keep him around long term, if I had a choice. If he can start hitting open looks with consistency he's an almost ideal role player at the SF position. That's not to say I'd be comfortable with JW getting 35+ minutes a game, unless he shows some drastic improvement.
DeRozan can also play some SF, though it will be an mismatch if the other team has a Teyshaun or Odom, for example.
Every now and again Amir can match up with a SF, too. I'd be comfortable with Amir guarding guys like Odom, Teyshaun, Hedo, etc.
Gaines is probably less useful to BC than an open roster spot as the trade deadline approaches. Also, BC is probably happy with the players that are healthy getting more minutes, especially guys like Wright, DeRozan, Bayless, Bargnani
and Ed Davis.