Atlantic is in the Copper Mountain Quad, but you access it south of Copper off CO 91 at Mayflower Gulch. Follow the snow covered road for about a mile, usually packed down, leave the road and head for the low point of the ridge (which is actually a creek that drains the basin west of Pacific) and climb through the trees to the ridge crest. Watch for cornices on the ridge, we tried it once after a fresh foot of snow had fallen and backed off due to the cornices, but otherwise the ridge is a nice winter ascent. From the same area you can access Crystal, Pacific (its west ridge is spicier than Atlantic's!) or Drift.
Most of the southern Gore have a lot of avy paths and I wouldn't recommend doing any peak that requires access from one of the major East Vail trails in winter - when I hike those trails in April and May I cross the many piles of slide debris from last winters devastation. Its impressive, especially the ones that cross the creek and start to go up the other side! You can, however, access Bald and "Outpost" from town, both have pages here on Summitpost, and stay out of those slide prone drainages. You can also access Uneva from Vail Pass, but there is a $7 fee to park at the pass in winter, which stinks because Uneva is on the other side of the road from the fee area.
There are some other options if you head over to Summit County or the Leadville area if you don't mind a longer drive.