The best would be to go for a day visit across to Zimbabwe and see the Falls from that side. You can simply organise a transfer from the Zambian side to the Zimbabwe side, any of the tour companies or your hotel in Zambia can organise this for you, it should cost you in the region of $20 per person depending on where you are staying in Zambia. You could also catch a taxi which would work out a bit cheaper, but you have to change taxis at the border post.
You then will probably (depending on your nationality) require a visa to enter Zimbabwe and another visa to re-enter Zambia (or rather buy a double entry visa when you first arrive in Zambia) These visas can be bought at the border post. So it gets a bit costly with all the visas, but it is well worth it.
