I also have a very easily over stimulated baby!! I remember those early days. He would get so wound up that he had such a hard time with his naps!
I tried to do all the big activities right after his nap -- so, tummy time, outing if necessary (although I really tried not to since it always let to a bad nap for us) playing in the play gym etc. Then, we would do walks outside, or I would put him in the carrier as I did some light housework. other things for the second half of A time - we would sing songs and rock, or read books.
I tired to to have too many toys around during the second half of A time, and no music or TV. - he does love music, but early on it was too much for him.
