Papallacta is located 67 km (40 mi) east of Quito on the route taken in 1542 by Francisco de Orellana. It crosses over the Andes through beautiful valleys on each side. Find a bus from Quito to Baeza or Tena and tell the bus driver/cashier that you want to get off in Papallacta. You can take the bus from the Supermaxi stop in Cumbaya (amongst other places), and there is about one every hour during the day and it costs about $2.5. It's a windy uphill road and the buses stop a lot and hence the journey takes about 2 hours.
Another option is to take the bus directly from the ticket office of Cooperativo Baños in Tumbaco (QJM2+3H Tumbaco, Ecuador). The price to Papallacta is $3 and you can buy the tickets directly at the office.
A taxi from the bus stop to the Termas costs $2 (Nov 2019), you might still get it for $1.5 though. Be advised that the taxi drivers will try to charge you more - so ask beforehand.
The thermal baths and the Reserva Ecologica Cayambe-Coca are the leading reasons to visit Papallacta. Otherwise, there aren't too many activities in this little town on the side of the hill.
The beautiful Reserva Ecologica Cayambe-Coca presents miles of lakes and trails in a preserved and secluded setting. There are no longer fees for access/camping/fishing. This reserve receives support from The Nature Conservancy, USAID, Parks in Peril and Rumicocha Ecological Foundation. The reserve is located high in the Andes around 13,000 feet so it receives quite a bit of rain. Access points are located past Termas de Papallacta as well as near the summit on the Via Interoceanica (as you reach the summit, look for a cement hut 1/4 mile off the road to the north).
Has good (and expensive) food and the very relaxing thermal pools. Note that there are the thermal baths (more inexpensive) as well as the Spa (price is much higher).
You can take a relaxing dip after your trip in the reserve or spend some time there. Baths: the prices are $9 (adults) or $4.50 (seniors/kids) as of November 2019. This does not include towels and lockers, which can be rented at the reception. You can rent a towel for $1 with a $5 deposit. The ticket is valid all day so you can enter and leave as you please. Spa: the prices are $23 (adults) and $15 (children) as of November 2019. The entrance includes a towel, bathing cap and a locker.
There is a tiny shop selling the most important groceries. Coming from the bus stop at the main road, follow the street going to the center. After passing Restaurant Papallacta and a huge sign saying "Hostal Coturpa" you will see it on your left. It is called Viveres, or so.
Trout is the most popular dish of the area.
There are a few hosteria's (small family run hotels) that are inexpensive. A few of them are located along the road from Quito to Papallacta. Ask the bus driver to stop in Papallacta and you will easily find one if you continue walking along the road.
There is a bus stop on the main road, go there and hail the first bus to Quito (about $2 - $2.50) or the other side if you want to go to Tena. Or hitchhike.