Depending on your skill level you may want to limit the difficulty of climb that you attempt.
Just because a trails distance is short, it does not mean that the climb will be easy or be completed quickly.
I have been on short distance climbs that took longer to climb then an alternate longer distance route.
Finding out the rise over run (elevation gain over distance of travel) is helpful when determining difficulty.
Also try to find pictures from someone who has climbed the peak before. Pictures can show the quality of trail maintenances on a route as well as help you to not get lost when on the trail.
Always make sure to check the weather for the area you will be climbing in; so you can prepare appropriately.
The weather at 14,000 feet is different then where most weather stations are reporting from.
For every 1,000 feet you gain, you can expect up to a 10degree (F) temperature change.
An afternoon lighting storm is normal in Colorado; so gather information about the weather patterns in the area that you will be climbing.
Will a 4X4 vehicle be necessary, just a high clearance one, or simply a passenger car?
Many trail head descriptions list both a passenger car and 4X4 vehicle parking areas.
If you plan to get to the 4X4 trail head, pack any equipment necessary to get out of a 4X4 situation (ex. shovel, jack, tow strap)
The best way to actually determine the amount of time it will take you to climb a route is by experience.
If you lack the first, then try to find a summit log that list a climb time and also includes information about the climber that sounds similar to your abilities.
If you are in good shape and distance does not bother you but time is an issue, then when in doubt just leave the trail head earlier.
Again experience plays into this decision, I always try to carry enough water for the entire hike. However, if I estimate the time on the trail to be longer then 6 hours then I'll bring the purifier.
Now I have heard one hiker claim, "The more I climb the less I take, because I seem to find myself using less of the gear."
I would have to counter with, the more you climb (over confidence) the more risk taking you do, and therefore you need the gear.
Also, the more climbing you do, the better in shape you are, so really the extra gear seems to weigh less anyway. So just take it.
Extra Clothing.
Extra Food.
Compass.
Map.
Sunscreen.
Camera.
First Aid.
Knife.
Two different means of fire starting (ex. lighter and matches).