use procedurals where you can, and sometimes you just have to use a very big texture. you can also take a repeating texture, and modify it except for the edges, then use UV mapping ( select all vertexes + U + reset ) , so everything reads on a per face basis, and you can interchange the textures to break up the repetition. ( edit: you would probably want to use ‘tex face’ button for this in materials. I think it’s still there in 2.6 ) but for something like concrete I would see how far I get using procedurals. try using a noise texture combined with a cloud texture maybe.
(edit) also, you can try combining tiling image textures at different scales, which will break up the repetition and can lead to interesting results. say you set one to tile three times in either direction, and set the other to tile 5.333 times.
(edit) also, what about using procedurals for the diffuse texture, and using a tiling image texture as a normals map.