I can't get on the game right now to get the coordinates of the other skeleton spawner I've found, but here's a link to a previous post I've made giving the coordinates of one skele spawner and one zombie spawner I've found in the tutorial world:
OK, I've got onto my game and written down the coordinates of all the dungeon spawners I've found so far:
Skeleton: X204, Y54, Z-99
Zombie: X199, Y56, Z-80
These two are very close to each other and great for making a double spawner trap.
Regular Spider: X-360, Y61, and Z64
This is a regular spider spawner located within a Mineshaft. There is also a Cave Spider Spawner relatively close by, but since I found this one, I destroy the cave spider spawners I find. As I recall, there have been about 5 in this huge, huge mineshaft or series of mineshafts (since sometimes you have to break a few blocks to get from section to section). I believe, however, the whole thing covers almost the entire quarter of the map.
Zombie (as reported in my earlier post): X-360, Y61, Z64
Skeleton (as reported in my earlier post) X254, Y35, Z-30