I was at Chester today and I enjoyed my first visit to the African Aviary. I saw all the advertised species, except the turacos and the robin-chats. I was very pleased to see that the weavers are building nests already.
Obviously the aviary will look better when the vegetation has grown a little more, particularly behind the pool, which looks rather bare. I quite agree that it would not suit dikdiks, which would feel uneasy and hide for most of the time.
There is room for some more birds, but I hope they don't intend to add any species that are much larger than the ones they have - I don't think there is enough space. But there are many species that might be suitable. It's a long time since I lived in Africa, but I could suggest wood-hoopoes, jacana (both of which are in London's African walk-throughs), laughing doves or blue-spotted wood doves, barbets and possibly coucals.
The other thught that crossed my mind was that if a smaller aviary was constructed with smaller mesh, you could keep a wonderful variety waxbills with mannikins and sunbirds, which would be equally African, but on a smaller scale.
Alan