First things first, I highly recommend you follow the Viva New Vegas guide, at least through the Base Finish section. Doing so will take care of a lot of bugs and memory issues, allowing you to use replacement textures with fewer problems. After following the VNV guide I am able to run the game with 194 mods and over 3GB of replacement textures with very few problems. I also highly recommend that you use Mod Organizer 2 to install and manage your game and mods since you can easily deal with things like the load orders of loose files. If you do not follow the VNV guide, then I wouldn't recommend using the landscape textures.

The first batch of files will be three separate things. First are replacement textures for the Radscorpion and Bark Scorpion, and the three base game Geckos. The idea behind these retextures was to make them a bit more detailed, but was mostly change to make them blend in with the terrain like a real animal would. See the images tab to get an idea of what I mean. They blend in perfectly with my landscape and rock textures, which will be uploaded later.

Next is my personal grass texture set. Just refer to the images tab to see if this is something you want or not, as it looks pretty different from the base game. Included with the grass textures are a new shrub texture and a tumbleweed texture, also shown in the images. If you prefer Hectrol's tumbleweed texture (which is very nice) load that after this in MO2. I grew up in an area covered in tumbleweeds, and just wanted my own take on them that looked a bit more sparse like the default, since that's how I remember them, but with a bit better resolution and color.

Last in the first batch is replacement Flagstone Wall textures. These are the stone walls you see all over the wasteland, particularly around Camp McCarran, the highways and bridges. Like the others, check the images tab to see an example.

Update - I have uploaded several new texture sets, including:
Roads and Asphalt textures, which cover both the roads and the generic asphalt textures used for things like parking lots and beneath the roads. Rubble textures for the different types of rubble piles used throughout the game. Sidewalk textures and the crack decals used on them, as well as several additional concrete textures that are used all over the game. The landscape textures seen in the screenshots I have posted which cover the majority of the games terrain, though there are a few ground textures not covered. Maybe in a future update I'll get those last few textures. Last are the rock textures in 4K and 8K. The 4K version should be fine for 1440p resolutions and below. At the moment there are no LOD textures for the rocks.

In general the textures will be 4K, with a few things at 2K. If you are curious why everything has been uploaded in smaller packs, it's partly because I wanted to get something uploaded quicker, and a smaller batch was quicker to get together, make sure it was all finished and ready, then pack it and upload it. But it's also to make it easier for people to pick and choose what they want to use. For instance if they like the sidewalk textures, but prefer another modder's landscape textures.