I located Marriott and it is near the Republiky area. It is about a 5- minute walk to Old Town Square where the astronomical clock is. I would go there definitely and view the parade of apostles on the hour. There are 4 statues next to the clock, two on each side - Death, the Turk, Vanity and Greed. They start moving and Death rings the bell as the two windows open where you see the apostles. The **** then crows which marks the hour. You can climb the tower as well to see a great view of the square. The following morning, you can go to the Jewish quarter since ABD does not cover that. All the synagogues are near each other as the Jewish were cloistered in that small area from about 500 years ago.
Your hotel is near the Powder Tower and Wenceslas Square. You can walk through those areas as well. Our guide did not recommend walking on Wenceslas Square at night as it is not a safe area. It is bustling with people though, so I leave that to your judgment.
I guess ABD walks on Charles Bridge as well? It's also good to walk on your own if you wish and climb the towers on either side. The weather is crazy right now, rain, snow and hail, all in one day, we have to make plans around the weather. There is an excellent trip report in the Trip Report thread so you can look into that and decide what you want to do during your pre- days.
