Udaipur is a better option. if you are starting from Delhi you can either go by car which will take you around 12 hours or you can opt for train which will be an overnight journey.
You can Visit Mussorie and Beyond. Route you may take is from Delhi -Rishikesh -Dehradun-Mussorie -Chakrata and Back via Haridwar. or you may visit jim corbett national park and Nainital.