Sometimes you can make the viewing area look like a feature of the exhibit,
for instance this viewing area looks into two exhibits -
JaguarsIf you plan areas to place your viewing areas when building the fences, then they can also look less out of place by building dents in the fences where you want to put them.
When using the elevated paths I usually find it's best to build them where you want them before putting down any trees/foliage, they always take me the longesst to look right though.
You could also try an island viewing area similar to the cover of AA - e.g.
Rhinos 1,
close up