What time in October are you going? Early October and late October are two different beasts. Also, do you have any experience with colder and/or higher altitude hiking? Hiking in early October can be nice (or not). Late October? More than likely icy, windy and cold.
Bierstadt is a walkup no matter what time of the year (still gotta be careful) and has easy access and easy camping all year around at the trailhead. Due to easy access AND hiking, it is considered a good beginner 14er.
Finally, 14ers ain't anything special. They are usually crowded.
A good place for shoulder season hiking is the Lost Creek Wilderness. It is my perennial favorite for early summer and late fall hikes.
Here's one idea:
http://www.pmags.com/joomla/index.ph...ilderness-loop
Get the map and you'll see others, too.