Though there are many touristy places around there are two places that attracts less people but are absolute gems. If you are a history buff visit Naggar castle with wooden architectures and piquant interiors. The other one is the Jogini Devi Waterfall which has an enchanting route going through forest with river Beas flowing by your side most of the time. You can find the whole route and detailed information here.
https://www.tripoto.com/community/offbeat-places-to-visit-in-manali