Here is some results with Optifine/MCpatcher vs Vanilla
(If you are wanting custom skies you will need to be at a render distance of 8 or higher.)
How to install:
- Download the resource pack.
- Open Minecraft, and go to Options->Resource Packs->Open Resource Packs Folder.
- Drag the zip file you downloaded into that folder.
- Select the pack, and you’re done!