Take a early morning train , say a 7 am train to MYS. Visit the rail museum and take a hotel and put in your luggage. You can then take a train or a bus and travel to Srirangpatna which is 45 mins away. The next day you can either opt for a KSTDC conducted city sightseeing tour or choose to do all the sights yourself by auto or bus.Get back to the hotel by 4-5 pm, Check out and take a 6 pm train back to Bangalore.