I personally love Uttarakhand for treks, considering that its far less crowded as compared to Himachal. You can check out Deoriatal-Chandrashila trek or valley of flowers trek because they are not that strenuous but still very beautiful.
I've been to Chandrashila and can personally vouch for it. You can read the following blog i had posted to get to know more about the place; https://www.tripoto.com/trip/a-place-i-ll-never-forget-chandrashila-5a65aaf908fa9