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.edit
"Tianguis"(in Valle it is held on Mondays, from 7 or 8 in the morning, til late in the afternoon) is like an outdoor flea market, with many different booths. Alot of the clothing and shoes being sold are used items that have been brought back from trips to the U.S. to sell. There are various booths that sell C.D.s and DVDs, at very low prices but decent quality. There are many booths that sell fresh foods, such as fruits and vegtables, fresh meat, and tortillas. This is also a great place to grab a bite to eat. There are alot of different booths where you can sit down and eat, but plan on getting there early to get a table. And don't worry about getting wet because all the booths are covered with tents. It is really a great place to go in Valle, you can find almost anything. From the guy who does a very good job cleaning and fixing jewlrey for a really low price to the best "carnitas" you will ever have. The people in Valle are very nice! Downtown Valle is very, very beautiful.
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.edit
In Valle there are tons of different ice cream shops, that have a very wide viarety of different flavors. Also there are ice cream carts in the town square. In my opinion the best kind to try is MAMEY. (a type of fruit, that tastes like a mix of cantalope and almonds.) The actual fruit is about the size of a mango, but is dark brown in color when ripe. ~~TIP~~ If you buy a "mamey" that is not quite ripe, wrap it newspaper and let it sit a day or two. (Also, U.S customs will not allow this fruit to be brought into the united states even if you remove the pit).