Quito

URL for this route is: http://www.gmap-pedometer.com/?r=4170580
Begin from teleferico, the cable car up the mountain.  Taxi's all know the place.  Opens at 10AM.  Be there at or before 10AM.  You want an early start on this.  $8.50 for a two way ticket for foreigners.  The hike commences at 13,450'.  Approximately 3 miles.  First 2 miles is pretty much getting to the volcanic outcropping, with relatively easy, uphill hiking.  Gets up to about 14,500 feet.  Follow the trail around the right of the rock, pass the scree and then head up.  The last half mile is harsh if, like me, you were hanging out at sea level just yesterday. You are now at around 15,000' and you have to fight your way up.
Considerations:  Weather can be a factor, ergo, start early.  Thunderstorms can be a bad thing when they are developing around you.  First time I did this, a massive storm developed on the summit while I was hiking down.  I could only imagine the terror of those that I had just passed going up as I was headed down.  Heaviest season for Thunderstorms is March-May (averaging about 6 inches a month), driest would be June-August (1.2 inches), when prevailing winds turn southern.  Temperatures are almost always the same year round.  You're at the equator, but you're at 13,000+ feet.  It will get cold.  Layers are the key to a comfortable climb.
Bring a lot of water.  Altitude will make you dehydrate (as will the exertion) more than you realize.  Bring snacks as well.
This is a primer route for Cotopaxi.