I'm going to be in and around Denver next week doing a bit of reconnaissance (I hate where I live and I'm thinking of moving). While I'm there, I'd like to ride a road bike up a hill. The thing is, I've been living in south Florida for 3 1/2 years and I've lost all of my climbing ability. Where are some good climbs near Denver that aren't too challenging? I'll be staying in Aurora but don't mind doing a bit of driving. Also, any recommendations on a cheap place to rent a road bike for a day?

Easy is in the eye of the beholder. I.e., today I led a ride where I went up a hill easily and the rider behind me walked the hill. However, he is 4 years older than I at 78yo and has had a stroke. But i digress. There is a nice trail in Lakewood which goes over Mt Carbon and down into Bear Lake Park. Not a huge climb, but one might find it a bit challenging. The trail is the Bear Creek Trail following Bear Creek from the Platte River Trail to Morrison.

This map may help

There is also famed Lookout Mountain, leaving west from Golden - a curvy road for several miles that only a few would classify as "easy."

Here is a route from Denver, but you could start anywhere along the way.

That map is perfect. Thanks!

That's not even easy in a car!

And that is a great map. I hope to find something like that on paper to hang up in my garage and/or carry with me as I start to go farther on my weekend rides.

I can cruise up it with barely any effort or at max. It is not a climb that is painful no matter how fast you are riding.
Lookout is the perfect climb for visitors, newbies, or for training.
I vote that the OP give it a try. In a relatively short time you can take in a nice view of the metro area.