Tile Set 1:
The first tile-set I would like to see is a forest/outdoor tile-set with running streams and rocky cliff-sides that the characters could climb. There would also be entrances for caves and underground passages, which would be apart of the second tile-set.
Tile Set 2:
The second tile-set would feature an underground cavern system with winding passages, which would lead to larger cavernous chambers, some of them having under ground pools of water. There should be rocky platforms for the characters to climb and traverse.
Tile Set 3:
The third tile-set would consist a collection of prefab buildings, which the characters could enter and explore. The village tile-set could be populated by the Game Master with merchants and NPCs. Some of these NPCs can give the characters quest and give them rewards for completing a quest; such as, coins, XP, magical artifacts or weapons and equipment. Some of these NPCs will be able travel through the village along predetermined paths set up by the Game Master.
These are the things that I would like to see done with the Map-Editing tool provided with the game.
Well I do like your Ideas but Outdoor environments won't be a "tileset" in the classic sense.
Those are no longer done in this age as a tileset, they're literally hand painted down and cannot be swapped in and out as components. So what we would likely get would be something akin to the way the NWN2 Toolset worked where you would height map an area, then paint the textures and throw in placables like houses and such.
I have actually been trying to push the Devs into releasing like one or two of their Outdoor/City environments as a "prefab". Perhaps all of them, I mean you could do a lot with the Dark Keep as a generic prefab, or using that dwarven town as a home base/hamlet type area to kick start an adventure for a party so they're not just dropped on their butts in the middle of a dungeon at the start of a module.
Basically it would allow for a setup to an adventure. I consider this type of thing a critical addition.
I definitely agree with the need for the Caverns (with water props) tileset. It is the one thing lacking to create a real full dungeon.
The Necropolis tileset we're currently using is VERY adaptable, I've been able to create both Crypt, Classic Dungeon, and Underground City type environments with it. That just needs more Props like weapon racks, porticullis, bunks, tables, fountains, trapdoors, stairwells, etc... but the base tileset for this is highly flexible and able to create multiple environments if you only get more of that they call "Props" which were called Placables in previous Toolsets.