I haven't been to Mandawa, but I have stayed very close to it, at a place called Fatehpur Shekhawati. Mandawa and Fatehpur have beautiful old havelis which will take you back in time. The small town has a laidback feeling where you would be lost in the old charm. Apart from the havelis, you also have temples to visit. I would suggest 'do jaanti balaji' 'dholi sati' and 'laxminath temple' in Fatehpur. Do jaanti and laxminath are famous ones. You can try moodi, kulfi and others outside do jaanti. It is also famous for a painting on its ceiling which has a chariot with seven horses. No matter from which direction you see, you feel the horses are coming in your direction. Beautiful illusion. Dholi sati has lot of temples inside it, all in white and marble and since it is less crowded, it will give you a feeling of peace and serenity. There is another temple called budhgar ji ki mandi which is at a small hilltop and has a very beautiful view. Hope you enjoy your trip :)