Figured I'd put in my two cents.
In all the below instances you MUST hit "p" to ignore all rejects when it comes up with a warning about not being able to place enough grasslands.Note: These were all found by my program, Ultrafinder: http://www.bay12games.com/forum/index.php?topic=38274.04x4 Legendary embark:The following contains a 4x4 with the following: Flux, aquifer, river, underground river, underground pool, magma pool, magma pipe, chasm, hfs, a small patch of sand and around 90 z-levels.
World Gen Perameters:[WORLD_GEN]
[TITLE:NEW]
[SEED:3072787075]
[HISTORY_SEED:3629570892]
[NAME_SEED:1364375378]
[DIM:65:65]
[END_YEAR:10]
[BEAST_END_YEAR:512:90]
[REVEAL_ALL_HISTORY:1]
[CULL_HISTORICAL_FIGURES:0]
[ELEVATION:1:400:1600:1600]
[RAINFALL:0:100:1600:1600]
[TEMPERATURE:25:75:1600:1600]
[DRAINAGE:0:100:1600:1600]
[VOLCANISM:0:100:1600:1600]
[SAVAGERY:0:100:1600:1600]
[ELEVATION_FREQUENCY:1:1:5000:5000:1:2500]
[RAIN_FREQUENCY:1:1:1:1:1:1]
[DRAINAGE_FREQUENCY:1:1:1:1:1:1]
[TEMPERATURE_FREQUENCY:1:1:1:1:1:1]
[SAVAGERY_FREQUENCY:1:1:1:1:1:10000]
[VOLCANISM_FREQUENCY:1:1:1:1:1:10000]
[GOOD_SQ_COUNTS:6:63:127]
[EVIL_SQ_COUNTS:100:250:500]
[PEAK_NUMBER_MIN:1]
[OCEAN_EDGE_MIN:0]
[VOLCANO_MIN:200]
[REGION_COUNTS:SWAMP:66:0:0]
[REGION_COUNTS:DESERT:66:0:0]
[REGION_COUNTS:FOREST:264:0:0]
[REGION_COUNTS:MOUNTAINS:528:0:0]
[REGION_COUNTS:OCEAN:528:0:0]
[REGION_COUNTS:GLACIER:0:0:0]
[REGION_COUNTS:TUNDRA:0:0:0]
[REGION_COUNTS:GRASSLAND:528:0:0]
[REGION_COUNTS:HILLS:528:0:0]
[EROSION_CYCLE_COUNT:275]
[RIVER_MINS:800:800]
[PERIODICALLY_ERODE_EXTREMES:1]
[OROGRAPHIC_PRECIPITATION:1]
[SUBREGION_MAX:5000]
[CAVE_MIN_SIZE:5]
[CAVE_MAX_SIZE:25]
[MOUNTAIN_CAVE_MIN:6]
[NON_MOUNTAIN_CAVE_MIN:12]
[ALL_CAVES_VISIBLE:0]
[SHOW_EMBARK_RIVER:2]
[SHOW_EMBARK_POOL:2]
[SHOW_EMBARK_M_POOL:2]
[SHOW_EMBARK_M_PIPE:2]
[SHOW_EMBARK_CHASM:2]
[SHOW_EMBARK_PIT:2]
[SHOW_EMBARK_OTHER:2]
[SHOW_EMBARK_TUNNEL:2]
[TOTAL_CIV_NUMBER:35]
[TOTAL_CIV_POPULATION:-1]
[PLAYABLE_CIVILIZATION_REQUIRED:1]
[ELEVATION_RANGES:528:1056:528]
[RAIN_RANGES:528:1056:528]
[DRAINAGE_RANGES:528:1056:528]
[SAVAGERY_RANGES:528:1056:528]
[VOLCANISM_RANGES:528:1056:528]
5x5 Legendary embark: Bugged site with a waterfall generating in the chasm tile.
The following contains a 5x5 with the following: All civs, Flux, Aquifer, River, Underground River, Underground Pool, Magma Pool, Magma Pipe (Exposed Volcano "The Slow Volcano"), Chasm (Exposed with a waterfall midway down... wtf?), Bottomless Pit (Exposed), HFS, Sand, Trees (Few), Sedimentary Stone (Shale), Economic Stone (Marble, Lignite), Bauxite, 83 z-levels, Elves at WAR.
World Gen Perameters:[WORLD_GEN]
[TITLE:VANILLA DREAM]
[SEED:58970622]
[HISTORY_SEED:2224483361]
[NAME_SEED:3296754253]
[DIM:65:65]
[END_YEAR:132]
[BEAST_END_YEAR:512:90]
[REVEAL_ALL_HISTORY:1]
[CULL_HISTORICAL_FIGURES:0]
[ELEVATION:1:400:1600:1600]
[RAINFALL:0:100:1600:1600]
[TEMPERATURE:25:75:1600:1600]
[DRAINAGE:0:100:1600:1600]
[VOLCANISM:0:100:1600:1600]
[SAVAGERY:0:100:1600:1600]
[ELEVATION_FREQUENCY:1:1:1:1:1:1]
[RAIN_FREQUENCY:1:1:1:1:1:1]
[DRAINAGE_FREQUENCY:1:1:1:1:1:1]
[TEMPERATURE_FREQUENCY:1:1:1:1:1:1]
[SAVAGERY_FREQUENCY:1:1:1:1:1:2500]
[VOLCANISM_FREQUENCY:1:1:1:1:1:1000]
[GOOD_SQ_COUNTS:6:63:127]
[EVIL_SQ_COUNTS:100:250:500]
[PEAK_NUMBER_MIN:1]
[OCEAN_EDGE_MIN:1]
[VOLCANO_MIN:75]
[REGION_COUNTS:SWAMP:66:0:0]
[REGION_COUNTS:DESERT:66:0:0]
[REGION_COUNTS:FOREST:264:0:0]
[REGION_COUNTS:MOUNTAINS:528:0:0]
[REGION_COUNTS:OCEAN:528:0:0]
[REGION_COUNTS:GLACIER:0:0:0]
[REGION_COUNTS:TUNDRA:0:0:0]
[REGION_COUNTS:GRASSLAND:528:0:0]
[REGION_COUNTS:HILLS:528:0:0]
[EROSION_CYCLE_COUNT:250]
[RIVER_MINS:300:300]
[PERIODICALLY_ERODE_EXTREMES:1]
[OROGRAPHIC_PRECIPITATION:1]
[SUBREGION_MAX:5000]
[CAVE_MIN_SIZE:5]
[CAVE_MAX_SIZE:25]
[MOUNTAIN_CAVE_MIN:6]
[NON_MOUNTAIN_CAVE_MIN:12]
[ALL_CAVES_VISIBLE:0]
[SHOW_EMBARK_RIVER:2]
[SHOW_EMBARK_POOL:2]
[SHOW_EMBARK_M_POOL:2]
[SHOW_EMBARK_M_PIPE:2]
[SHOW_EMBARK_CHASM:2]
[SHOW_EMBARK_PIT:2]
[SHOW_EMBARK_OTHER:2]
[SHOW_EMBARK_TUNNEL:2]
[TOTAL_CIV_NUMBER:35]
[TOTAL_CIV_POPULATION:-1]
[PLAYABLE_CIVILIZATION_REQUIRED:1]
[ELEVATION_RANGES:528:1056:528]
[RAIN_RANGES:528:1056:528]
[DRAINAGE_RANGES:528:1056:528]
[SAVAGERY_RANGES:528:1056:528]
[VOLCANISM_RANGES:528:1056:528]
6x6 Legendary embark: - If you aren't using Mike Mayday's DFG with this world gen, the mineral layouts will be different.Features: All neighbouring civs, Flux, Aquifer (2 Z-Levels), River (Brook: Coalsprings), Underground River, Underground Pool, Magma Pool, Magma Pipe, Chasm, Bottomless Pit, HFS, Sand, Trees (Plentiful), Sedimentary Layer (Limestone) + More bauxite than you'll ever need, Goblins at WAR (With civ: "The Labor of Drills")
World Gen Perameters:[WORLD_GEN]
[TITLE:DWARVEN DREAM]
[SEED:3770113108]
[HISTORY_SEED:1089476479]
[NAME_SEED:1438436562]
[DIM:65:65]
[END_YEAR:132]
[BEAST_END_YEAR:512:90]
[REVEAL_ALL_HISTORY:1]
[CULL_HISTORICAL_FIGURES:0]
[ELEVATION:1:400:1600:1600]
[RAINFALL:0:100:1600:1600]
[TEMPERATURE:25:75:1600:1600]
[DRAINAGE:0:100:1600:1600]
[VOLCANISM:0:100:1600:1600]
[SAVAGERY:0:100:1600:1600]
[ELEVATION_FREQUENCY:1:1:1:1:1:1]
[RAIN_FREQUENCY:1:1:1:1:1:1]
[DRAINAGE_FREQUENCY:1:1:1:1:1:1]
[TEMPERATURE_FREQUENCY:1:1:1:1:1:1]
[SAVAGERY_FREQUENCY:1:1:1:1:1:2500]
[VOLCANISM_FREQUENCY:1:1:1:1:1:1000]
[GOOD_SQ_COUNTS:6:63:127]
[EVIL_SQ_COUNTS:100:250:500]
[PEAK_NUMBER_MIN:1]
[OCEAN_EDGE_MIN:1]
[VOLCANO_MIN:75]
[REGION_COUNTS:SWAMP:66:0:0]
[REGION_COUNTS:DESERT:66:0:0]
[REGION_COUNTS:FOREST:264:0:0]
[REGION_COUNTS:MOUNTAINS:528:0:0]
[REGION_COUNTS:OCEAN:528:0:0]
[REGION_COUNTS:GLACIER:0:0:0]
[REGION_COUNTS:TUNDRA:0:0:0]
[REGION_COUNTS:GRASSLAND:528:0:0]
[REGION_COUNTS:HILLS:528:0:0]
[EROSION_CYCLE_COUNT:250]
[RIVER_MINS:300:300]
[PERIODICALLY_ERODE_EXTREMES:1]
[OROGRAPHIC_PRECIPITATION:1]
[SUBREGION_MAX:5000]
[CAVE_MIN_SIZE:5]
[CAVE_MAX_SIZE:25]
[MOUNTAIN_CAVE_MIN:6]
[NON_MOUNTAIN_CAVE_MIN:12]
[ALL_CAVES_VISIBLE:0]
[SHOW_EMBARK_RIVER:2]
[SHOW_EMBARK_POOL:2]
[SHOW_EMBARK_M_POOL:2]
[SHOW_EMBARK_M_PIPE:2]
[SHOW_EMBARK_CHASM:2]
[SHOW_EMBARK_PIT:2]
[SHOW_EMBARK_OTHER:2]
[SHOW_EMBARK_TUNNEL:2]
[TOTAL_CIV_NUMBER:35]
[TOTAL_CIV_POPULATION:-1]
[PLAYABLE_CIVILIZATION_REQUIRED:1]
[ELEVATION_RANGES:528:1056:528]
[RAIN_RANGES:528:1056:528]
[DRAINAGE_RANGES:528:1056:528]
[SAVAGERY_RANGES:528:1056:528]
[VOLCANISM_RANGES:528:1056:528]