Yes play Genesis mod I can vouch that there are a ton of elves around to um "play" with as I have been meeting them very frequently in ambushes when running around in their territory. The Dusk elves are cool though and they even have towns and good weapons and armor for you.
If you do aim for Genesis mod, the 'Good' elves are the Dusk and Dunedwellers, those you 'want' to kill due to equal ethics to vanilla DF are the Sylvans.
If you do want to kill Elves (wondering why, as it's the ethics that differentiate them in adventure mode), go into the raw folder from the DF folder > objects > entity default.
Then do this:
'Ctrl + f'ind the word 'Elf' then scroll a bit down until you see:
[DEFAULT_SITE_TYPE:TREE_CITY]
[LIKES_SITE:TREE_CITY]
[TOLERATES_SITE:CITY]
[TOLERATES_SITE:TREE_CITY]
[TOLERATES_SITE:CAVE_DETAILED]
[START_BIOME:ANY_FOREST]
[BIOME_SUPPORT:ANY_LAKE:1]
[BIOME_SUPPORT:ANY_FOREST:3]
[BIOME_SUPPORT:ANY_RIVER:1]
[TREE_CAP_DIPLOMACY]
This designates where their race starts. Currently, you cannot see any Forest homes nor Mountain Halls in adventure mode, nor in fortress mode for that fact.
Replace that with:
[DEFAULT_SITE_TYPE:CITY]
[LIKES_SITE:TREE_CITY]
[LIKES_SITE:CITY]
[TOLERATES_SITE:CITY]
[TOLERATES_SITE:TREE_CITY]
[TOLERATES_SITE:CAVE_DETAILED]
[START_BIOME:ANY_FOREST]
[BIOME_SUPPORT:ANY_LAKE:1]
[BIOME_SUPPORT:ANY_FOREST:3]
[BIOME_SUPPORT:ANY_RIVER:1]
[TREE_CAP_DIPLOMACY]
So they would start out in 'human' cities.
And for another unrelated note, if you did mod in Elven diplomats and do not want to get the tree-capping rule, just delete the [TREE_CAP_DIPLOMACY] from there. Not fun though.
Edit: Welcome to the Bay12 Forums Telekinesis!