Sounds to me that a 70-200 f/4 or f/2.8 with good macro function (1:3 or 1:4) might be the ticket for you. For a tighter budget a 70-300 with a good macro function might also do the trick.

Tamrons 70-200 f/2.8 has an excellent magnification of 1:3.1, which is much closer than the Canon counterparts can get. Its also a lot cheaper. Good for flower type closeups and sports, a very solid hybrid.

Anyway that would be my choice for lens in the two shooting scenarios you mentioned. (Macro+sports)