1.c4 e5 2.g3 d6 3.Bg2 Be6??

The first continuation that comes to mind is 4.Bxb7 Nd7 5.Bxa8 Qxa8. White is up the exchange and a pawn, however: black's rook was far from becoming active, white has already spent many tempi developing the bishop. Also, the light squares around the king and the a8-h1 diagonal are dominated by black, 6.f3 seems awkward. The c4 pawn will also be lost. Is this really so great for white? I'm not sure.

5.Bxb7 Nd7 6.Bg2 is dubious too, the a8 rook gets activity and black will win back the pawn.

So what can white do? Should he just ignore the hanging b7 pawn and develop?

Another idea I had was 5.Qb3 which seems to get a winning position without giving black any dangerous counteplay. Any thoughts or feedback?

I don't see what's your problem with winning an exchange for free...
Black doesn't have any good way to use your light squares. White is just much better. 

Caedrel IS FESES!