From Mexico City, take the metro to the Western bus terminal. Multiple companies run an hourly service to Valle for 100MXN.
From Toluca airport, take a taxi direct to Valle.
Taxis. They're eveywhere.
Monarch butterfly migration. If you're in the area in late December to early January, you should go see one end of the massive monarch butterfly migration. If you want to hike up the mountain to see them gathering in the their tree sanctuary, this can be a half-day excurusion.
Bat Divad. rock climbing, scuba diving, mountain biking
Doña something-or-other, City square (Zocalo). There is an old lady who has a little portable kitchen that makes the most delicious pambasos ever. If you've never had one, this is the place. Just ask for the pambasos lady. If she's not there, there are other street vendors who make delicious food.
Lots of accomodations to find at Todo Valle. Already decent accomodation for 2000MXN/week/person.