Keeping in view the short time span available that includes to and fro journey also, i would recommend a trip to a nearby resort where the travel time is less and relaxing time is more. 1. You can go to Aahana resorts Ramnagar Uttrakhand, a nature resort to give you a peaceful time over the weekend. As it is located in the close vicinity of Jim Corbett National Park, the weekend trip will be full of fun and excitement. Travel time 5 hrs from Delhi by Car. Detailed article is there in my section to know more about the property 2. You can go to The Golden Tusk Ramnagar Uttrakhand, a nature resort to give you a peaceful time over the weekend. As it is located in the close vicinity of Jim Corbett National Park, the weekend trip will be full of fun and excitement. Travel time 5 hrs from Delhi by Car. A detailed article is there in my section to know more about the property. 3. You can head to Morni Hills, Haryana where a small resort built on the banks of Tikar tal lake and in the foothills of Shivalik Mountain Range will make it a memorable trip and give you time to spend together. The add-on attraction can be the Timber trail resort which is built on a hill and the access is through a rope way cable car system. You can either choose to stay on the hill resort skipping the morni hills stay or can spend small time over there and then proceed to Morni hills resort for the weekend
Go Rishikesh stay at Yogniketan by Sanskriti which is just 30min from Dehradun/Jollygrant airport. Stroll around and enjoy late night walking at Ganga ghat (literally from 12 am till early morning) as the hotel is on the ghat itself so you feel like its your private ghat at night. Do river rafting next day and then roam around in evening and then board your flight next day. Enjoy local chats, visit Jhula's, be part of famous Parmarth Ganga Aarti, Visit scenic 'Tera Manzil' temple or Trimbakeshwar Temple, Dev prayag or Masoorie from there if you have more time.