Texturing large surface

If you search for 'Mega Texture' then you should find something for very large surfaces. You can also do a repeating texture that is procedurally modified based on position, or even do tiling of separate textures that depend on position. Is there something in particular you are trying to get working?

Would wrapping the texture work - or are you looking to do a texture blend ?

Look into Procedural Texturing.

If you can't afford the cost of run-time generation of the textures on your target HW, go with blending of different materials - e.g. sand, rock, snow, gravel,.... in a shader.

This way, if your terrain mesh is reasonably detailed and with different features (rolling hills + valleys + sharp peaks), the texturing will look pretty good.

Even a primitive combination of a slope (precalculated&stored per vertex) +elevation gives really nice results and might even be enough.

This is a screenshot of a very old [per-vertex-blending] implementation (just slope and elevation) of mine without blending in pixel shaders (e.g. this works on a REALLY old HW - GeForce 2):