For the first time, i saw the craters of the moons through a 20" refracting telescope at the Chabot Space and Science Center, near Oakland, CA . It was impressive, as the dome was opened out and this telescope which was possibly more than 300 feet in length, was positioned to point to the moon. The entire telescope was swung and rotated vertically about its center, easily. The dome rotated and positioned the telescope and the viewing angle to capture the best view of the moon's craters, about 250,000 miles away! That was incredible, when experiencing first hand.
The people working there were very knowledgeable (no surprise!) and friendly and were patiently answering all the questions.
We (myself, kids and chitra) also saw Jupiter and its 3 moons from another 8" telescope. The moons were not visible to the naked eye.
The experience was inspiring enough that the kids immediately wanted me to get a telescope. What surprised me was the fact that 7-yr old Sadhana was also asking interesting questions to the crew there, since i was of the view that Sadhana was probably not ready for this experience. Evidently, Sahana was quite interested.
Besides the Telescope viewing, the exhibits, facts and presentation of all aspects of space - The solar system, stars, Universe, moon landing, the rockets, telescopes - everything was grand, comprehensive, artistic and solid - the experience handed, etched the science and facts so well, i would say this center is a must-see for all, and something to be cherished by all Californians.

As a bonus, the night-time view of the city of Oakland and Berkeley from the hill top was breath-taking enough, it is in itself worth a visit.