Just to be sure...

I've got both DLCs, and the only mods I use are the 3 Unofficial Patches and the 3 High Res Texture Packs.

Currently, my load order is:

• Dawnguard
  
• Hearthfire
  
• Unofficial Skyrim Patch
  
• Unofficial Dawnguard Patch
  
• Unofficial Hearthfire Patch
  
• High Res Texture Pack 1
  
• High Res Texture Pack 2
  
• High Res Texture Pack 3

Is that the best order?

And, when I add in my own mod (to change cell respawn times), where should it be in the load order?

Thanks.

I believe the official high-resolution texture packs should be loaded before unofficial patches. Why are there three High Resolution Texture Packs, I don't know.

Your mod should be loaded at the bottom of your loaded to avoid conflicts.

With BOSS I got the following load order:

1. Dawnguard
2. Hearthfire
3. High Res Texture Pack 1
4. High Res Texture Pack 2
5. Unofficial Skyrim Patch
6. Unofficial Dawnguard Patch
7. Unofficial Hearthfire Patch

I don't recognize High Res Texture Pack 3. Does that really exist?

I think he means the unofficial HD DLC Fix mod. But yeah, your mod should come last of the ones you've mentioned.