An infinite source of flowing water is *always* useful. Then again, I tend toward playing Single-Pick Challenge forts - no aquifer = no surviving past the first couple months, in those circumstances.
Anyways, I was playing around with advanced parameters, and came up with this:
[WORLD_GEN]
[TITLE:MEDIUM REGION]
[SEED:Get Dorfed!]
[HISTORY_SEED:No, Really]
[DIM:129:129]
[EMBARK_POINTS:1324]
[END_YEAR:350]
[BEAST_END_YEAR:125:5]
[REVEAL_ALL_HISTORY:1]
[CULL_HISTORICAL_FIGURES:0]
[ELEVATION:100:400:3200:3200]
[RAINFALL:0:100:3200:3200]
[TEMPERATURE:25:75:200:200]
[DRAINAGE:0:100:200:200]
[VOLCANISM:15:100:200:200]
[SAVAGERY:0:100:200:200]
[ELEVATION_FREQUENCY:2:4:6:3:2:1]
[RAIN_FREQUENCY:2:5:4:3:2:1]
[DRAINAGE_FREQUENCY:1:1:1:1:1:1]
[TEMPERATURE_FREQUENCY:1:1:1:1:1:1]
[SAVAGERY_FREQUENCY:2:1:2:3:4:7]
[VOLCANISM_FREQUENCY:2:1:2:3:5:8]
[MINERAL_SCARCITY:250]
[MEGABEAST_CAP:45]
[SEMIMEGABEAST_CAP:80]
[TITAN_NUMBER:15]
[TITAN_ATTACK_TRIGGER:80:0:100000]
[DEMON_NUMBER:28]
[NIGHT_TROLL_NUMBER:14]
[BOGEYMAN_NUMBER:14]
[VAMPIRE_NUMBER:14]
[WEREBEAST_NUMBER:14]
[SECRET_NUMBER:28]
[REGIONAL_INTERACTION_NUMBER:28]
[DISTURBANCE_INTERACTION_NUMBER:28]
[EVIL_CLOUD_NUMBER:20]
[EVIL_RAIN_NUMBER:20]
[GOOD_SQ_COUNTS:13:125:251]
[EVIL_SQ_COUNTS:50:500:1000]
[PEAK_NUMBER_MIN:10]
[PARTIAL_OCEAN_EDGE_MIN:0]
[COMPLETE_OCEAN_EDGE_MIN:0]
[VOLCANO_MIN:25]
[REGION_COUNTS:SWAMP:0:0:0]
[REGION_COUNTS:DESERT:0:0:0]
[REGION_COUNTS:FOREST:0:0:0]
[REGION_COUNTS:MOUNTAINS:0:0:0]
[REGION_COUNTS:OCEAN:0:0:0]
[REGION_COUNTS:GLACIER:0:0:0]
[REGION_COUNTS:TUNDRA:0:0:0]
[REGION_COUNTS:GRASSLAND:0:0:0]
[REGION_COUNTS:HILLS:0:0:0]
[EROSION_CYCLE_COUNT:0]
[RIVER_MINS:10:10]
[PERIODICALLY_ERODE_EXTREMES:0]
[OROGRAPHIC_PRECIPITATION:1]
[SUBREGION_MAX:5000]
[CAVERN_LAYER_COUNT:3]
[CAVERN_LAYER_OPENNESS_MIN:90]
[CAVERN_LAYER_OPENNESS_MAX:100]
[CAVERN_LAYER_PASSAGE_DENSITY_MIN:0]
[CAVERN_LAYER_PASSAGE_DENSITY_MAX:40]
[CAVERN_LAYER_WATER_MIN:25]
[CAVERN_LAYER_WATER_MAX:100]
[HAVE_BOTTOM_LAYER_1:1]
[HAVE_BOTTOM_LAYER_2:1]
[LEVELS_ABOVE_GROUND:20]
[LEVELS_ABOVE_LAYER_1:5]
[LEVELS_ABOVE_LAYER_2:1]
[LEVELS_ABOVE_LAYER_3:1]
[LEVELS_ABOVE_LAYER_4:1]
[LEVELS_ABOVE_LAYER_5:2]
[LEVELS_AT_BOTTOM:1]
[CAVE_MIN_SIZE:5]
[CAVE_MAX_SIZE:25]
[MOUNTAIN_CAVE_MIN:30]
[NON_MOUNTAIN_CAVE_MIN:60]
[ALL_CAVES_VISIBLE:0]
[SHOW_EMBARK_TUNNEL:2]
[TOTAL_CIV_NUMBER:75]
[TOTAL_CIV_POPULATION:15000]
[SITE_CAP:5000]
[PLAYABLE_CIVILIZATION_REQUIRED:1]
[ELEVATION_RANGES:0:0:0]
[RAIN_RANGES:0:0:0]
[DRAINAGE_RANGES:0:0:0]
[SAVAGERY_RANGES:0:0:0]
[VOLCANISM_RANGES:0:0:0]
There aren't any towers that I noticed, but I do like the wide swathes of magenta on the map. Also, note that there are roughly double the MegaBeasts, Titans, and cave populations than usual. I dunno; use this, tweak it, throw it away - just looks like a fun sort of map, littered with nifty places to set up shop.
BTW - are we setting a population cap?