I know a lady who takes children from the zone in for a couple of weeks holiday every year, lovely kids, polite and very appreciative apparently.We had a charity for years here run by Adi Roache (who later ran for president) and her charity still takes children affected to stay in homes for a month or more and get good freah air and whatever medical treatment is organised/needed. She did a book - Children of Chernobyl- a while back to help promote the charity & cause and the photos and stories would make a blind man weep. Would also make you hesitate a bit before taking any plunge - I think a some of the organisers who went over there in the first few years have all had obscure rare cancers and unexplained debilitating illnesses. Frightening stuff.
When in the zone most people tend to have a dosimeter with them at all times and the background radiation is a little higher than usual but nothing serious as long as exposure is not for long periods hence the good folk of Chernobyl are only allowed to stay for 15 days then have to be elsewhere for 15 days thus limiting exposure.
There are hot spots and some very very hot spots but as long as you take notice of the dosimeters you should be ok.
A few days in the zone will give less exposure than the flight over as long as you are sensible.