In a solo game, do you get bonuses on powers like Boon of Vigor that usually only happen if you target another player?

In a solo game, do you get bonuses on powers like Boon of Vigor that usually only happen if you target another player?

No.
You can target yourself with powers that say 'Another Player', but any effects that are conditional on targeting someone else do not activate. (Rulebook p. 22)