Go for Yhai! they provide the best experience at a low cost! as it is a govt. travel organization, don't expect luxury accommodations, but worth the try!! all the best
I have planned such a trip in 2018. You can start from Pathankot via Manali. after traversing , you can rent a vehicle of your preference and head towards Spiti, there you can stay at Kaza. from there you can go to Leh via zhanskar. finally to ladakh
I am a freelancer and i travel with my laptop. I'm working all the time. It feels great; at least my office is not the same boring walls and the same chair. It's different everytime. Sometimes i'm at hills, other times i'm working at a pool side. However, these things can be distracting as well, but adhering your routine will make things work.
4 Day is a lot of time... Start from the top Narkanda, then kufri, Shimla, solan. If you are going Chail don't forget the resort in water.. Its amazing, Also, Chail is another route and not in one line.