One of the best ways to find deserts/savannahs/mesas is to crosss the ocean. It's not a great problem now.
Of course, it can't guarantee a 100% result but is worth trying.
I used AMIDST on my existing world and my friends world (created in 1.5.1) - savannah tended to be quite common, but the mesa biome was quite rare, over 4000 blocks north and 6000 blocks east in my world, and my friends world was nearly twice the distance. Still, I have a Nether Minecart station, so sending a line out to the mesa biome will be 1/8 the mining distance of the overworld route. I think maybe the use of Nether portals to cover long distances maybe more of an option for SP people to consider if they don't use it already ...
I am posting this just as another Minecrafter not as a moderator.
I suggest that anyone searching for a seed with specific biome or structure characteristics download and try out Amidst.
Amidst v3.4 is the latest working copy of an ongoing project that currently works well on Windows systems and somewhat well on Macs and PCs running other OSs. It quickly shows you what the biome map will be and about a 90% accurate prediction of surface structures.
It does accurately show the locations of the three strongholds that are present in every world. The download links are to be found in the OP of this topic.
OBTW - Amidst is NOT a mod. It is a separate free application that uses some of the code in the selected version of Minecraft's .jar to produce the biome map of the world a seed will produce. Also, it has been found that it will not work with a modded version of Minecraft that changes the world generator.
There are no dangerous weapons. There are only dangerous people. R.A. Heinlein
If you aren't part of the solution, then you obviously weren't properly dissolved.
As I've posted elsewhere, I've run into the same problem with my worlds: Nothing but temperate biomes (X-hills, Roofed forest, regular forest (with the occasional flower varient), Birch forest, taiga, plains and swamps) all the way to the edges of a fully-expanded in-game map (2048x2048 blocks), and only a single plains village along the edge of a small ocean (that I dubbed "Bikini Bottom" ) in the most recent case.
If I don't get a start where I can find Jungles or Savannah within a reasonable distance from start, I'm just going to go back to playing 1.6 until the Rei's Minimap, the Portal Gun mod, Industrial Craft II (or Thermal Expansion) and Modular Power Suits updates to 1.7, because you're going to need some faster mode of travel than mere horses or minecarts to find anything interesting. Having to travel over 2K blocks just to find something different isn't quite as annoying if you can zap a portal at your home base, then power glide/power run in your kick-ass power armor out to where you need to go, pop down the opposite portal and have an instantaneous means of travel between your bases...
Personally I'd prefer that they made the temperature gradient adjustable (i.e. allow the player to chose the maximum radius of temperature zones, i.e. so I could make it so that any given gradient has a radius of 256 blocks instead of the present ~1.5K that it seems to be at the present).
If anyone needs savannahs I got plenty of them. Hell I found plains and a flower forest and got optimistic only to find out that both of them are 'surrounded' by deserts and savannahs, at X=3000 I did find a mesa though, so I guess that's something, but I really want to find roofed forests and mega taigas which so far have managed to hide from me and my horse,
Of course, it can't guarantee a 100% result but is worth trying.
They are rare because they are valuable!
Its a good thing
http://www.minecraftforum.net/topic/1845612-a-guide-to-youtube-minecraft-letsplaystipsideas-followed-the-guide-add-your-channel/
Mintutor now works in 1.13!
MrKite & Mc_Etlam ... I salute you!
I suggest that anyone searching for a seed with specific biome or structure characteristics download and try out Amidst.
Amidst v3.4 is the latest working copy of an ongoing project that currently works well on Windows systems and somewhat well on Macs and PCs running other OSs. It quickly shows you what the biome map will be and about a 90% accurate prediction of surface structures.
It does accurately show the locations of the three strongholds that are present in every world.
The download links are to be found in the OP of this topic.
OBTW - Amidst is NOT a mod. It is a separate free application that uses some of the code in the selected version of Minecraft's .jar to produce the biome map of the world a seed will produce. Also, it has been found that it will not work with a modded version of Minecraft that changes the world generator.
There are no dangerous weapons. There are only dangerous people. R.A. Heinlein
If you aren't part of the solution, then you obviously weren't properly dissolved.
The latest release of Amidst, version 4.6 can be found here:
https://github.com/toolbox4minecraft/amidst/releases
You should probably also read this:
https://www.minecraftforum.net/forums/mapping-and-modding-java-edition/minecraft-tools/2970854-amidst-map-explorer-for-minecraft-1-14
You can find me on the Minecraft Forums Discord server.
https://discord.gg/wGrQNKX
If I don't get a start where I can find Jungles or Savannah within a reasonable distance from start, I'm just going to go back to playing 1.6 until the Rei's Minimap, the Portal Gun mod, Industrial Craft II (or Thermal Expansion) and Modular Power Suits updates to 1.7, because you're going to need some faster mode of travel than mere horses or minecarts to find anything interesting. Having to travel over 2K blocks just to find something different isn't quite as annoying if you can zap a portal at your home base, then power glide/power run in your kick-ass power armor out to where you need to go, pop down the opposite portal and have an instantaneous means of travel between your bases...
Personally I'd prefer that they made the temperature gradient adjustable (i.e. allow the player to chose the maximum radius of temperature zones, i.e. so I could make it so that any given gradient has a radius of 256 blocks instead of the present ~1.5K that it seems to be at the present).
The Wak Ka' Múul Chronicles: My Minecraft series on YouTube
I think I am using Admist.