For fantastic views over Quito, I suggest you climb the Basilica. The entry fee to the towers is only $2 and is a fun activity for anyone.
The stairs get quite steep at the top but your efforts will be rewarded by the views over Quito´s rooftops and the mountains that surround the city.
There is a pretty looking cafe at the top of the south tower, a lovely spot to admire the scenery and to catch your breath!
For more on what to do in Quito, check out my city guide.