Lake McConaughy is the best spot within driving distance.

Auroa resovoir is the best spot near the city. To kite in Aurora though you need to be able to stay up wind, it's not a beginners location, although that doesn't sound like a problem for you. I don't kite there that often so certainly some locals could provide better info. SE works best, it's always gusty but I've had some great sessions there. The launch area is next to the dive area (which you have to stay out of). You will need to buy either a day pass or an annual permit to use the park and they will want to inspect your vessel (boards) for zebra muscles. When you pull up to the entrance they can probably give a lot more info and the rules. The locals are very friendly and will also provide you with more knowledge. Have fun.

Forgot to add the winds tend to be pretty light in the summer, spring and fall are the best times but you might still get some good days in the summer.

alpower - I used to live near Chatfield reservoir many years ago & remember that most evenings there was a pretty strong local wind that kicked up from the uneven heating/cooling effects and outflow from the hogback and foothills.
Its a small lake and I bet on the weekends its full of powerboats, so I bet its not the best place.

That's why Aurora is best, it's east of the city.

I just moved from Denver - the best place to go is unfortunately Lake Mac in Nebraska. The winds on the front range are very volatile and it is not unlikely that you could get hit by a massive gust in any season there. There was apparently some sort of incident on Aurora reservoir recently:

http://kdvr.com/2012/06/04/kite-surfers ... reservoir/

Just be safe. The wind will be very gusty and can change directions incredibly quickly.