So I'm basically looking for a Large Continent (Maybe 4,000 x 4,000) surrounded by a few thousand blocks of ocean. I know it's a huge thing to ask, but I'm really looking to start an SMP with my friends, and I need a large, isolated space to tell my story. I just need something with a good biome diversity, some structures (Villages, Temples, a Stronghold, etc..) and just some interesting terrain. Please help if you can. Thanks!
I suggest that you download Amidst v4.6, run it, select a VANILLA profile for the PCMC version you prefer,
and start hitting Ctrl-R. (the link is at the bottom of this post)
That will cause Amidst to display the biome maps of random seeds.
Ctrl-H in Amidst gives you the seed input dialog.
Amidst 4.6 works with MC Java releases 1.0 up to and including 1.16.5.
Hint: Place Amidst in it's own folder and create an empty file in that folder named "history.txt".
When Amidst starts up it will detect that file and from then on will log of every seed that it displays to the end of that file.
That way, if you hit Ctrl-R too quickly you can find out what the seed was of the previous map and redisplay it.
I use Notepad++ as my default text editor as it will update itself if Amidst adds a line to history.txt while it is open in a Notepad++ tab.
Performance note: If you are looking for a specific biome at spawn for a 1.13.2 and above world, I suggest that you run Amidst with a VANILLA 1.12.2 profile to search (the world maps will be displayed about 3 times faster than with later releases). Once you find a world that seems to fit your needs hit Ctrl-C to copy the seed to your clipboard and switch profiles to a VANILLA copy of your desired release and use Ctrl-N Ctrl-V to enter that seed back into Amidst and display the desired map.
BTW: It is possible to have multiple instances of Amidst running at the same time. I currently have one for 1.12.2 and another for 1.13.2, 1.14.4, or 1.15.2 running.
That way I can search random seeds quickly with 1.12.2 and if I see an interesting one copy and paste the seed into the much slower 1.13.2 / 1.14.4/ 1.15.2 instance.