We did Jaipur to Auli last week 2018. We took the route Jaipur-Delhi-Khatuli-Bijnor-Lansdowne-Srinagar-Rudraprayag-Pipakkoti and than Joshimath. (We skipped Haridwar-Rishikesh-Devprayag to avoid traffic) Lansdowne route is quite scenic and good as compared to Rishikesh one.
Day 1- Jaipur to Lansdowne
Day 2 - Lansdowne to Pipalkoti
Day 3- Visit Joshimath and Auli
Day 4-5 return (night halt in Lansdowne).
You can also skip prior booking to any hotel as you will get GMVNL TRH in most of the places. Night drive is also not suggested in hilly area.
Not possible to cover Jaipur-Auli in one day. Rishikesh to Joshimath is around 8-9 hours. Best is to start early morning from Jaipur and stay overnight at Rishikesh. If plan early, you can witness Ganga aarti at triveni ghaat Rishikesh. Next morning you can travel to Joshimath. Since you are planning to go Auli and it is only reachable by cable car from Joshimath. Keep in mind that last trolley for Auli is around 4 or 5 p.m. confirm from gmvn before you go.
Make sure the hill drive is done by day. Lot of landslides between Karnprayag and Joshimath. At many places you have to wait till JCB clears the rocks on road. So timing of Google maps is useless here. Long line of cars keeps waiting then one side is allowed to cross. So start early on second day after night halt. You can take Lansdowne route if you like scenic hill drives. Main route with traffic is via Rishikesh. Or Kotdwara Najibabad.
It is a lovely drive along Ganga:
http://traveltwosome.com/valley-of-flowers/
