La Union is about 6 hours from Manila if you're taking a bus at night and about 7 to 8 hours if you're traveling at daytime. But it'll just take you 5 hours if you're traveling by car especially if you're going to take the SCTEX rather than the NLEX. There are also rumors that the expressway will be extended to La Union so travel time may actually be cut to only 4 hours. Going back on track...
1. Ride a bus bound for Laoag, Vigan or Abra. There are several bus companies serving the Ilocos Region but my personal fave is Partas. First hourly trip is at 5:00 AM and last trip departs at 12 MN. Fare is around P400 to P500 depending on the bus type and class. Map of Partas Cubao terminal here.
2. Tell the conductor that you're going to La Union. So if he asks you where exactly and you don't know what to answer, then read along. This whole blog post is an introduction to La Union so somewhere over here you'll find a reason or two to visit ze province.
You can also take a plane to San Fernando, La Union. The only airline that serves La Union is ZestAir. ZestAir flies to La Union 3x a week. Check the flight schedule here.
Most people go to La Union to surf. It has become a hot spot in recent years especially for those who want to try surfing but have limited time and budget. Siargao, the country's more popular surfing destination, is a wee bit further and heavier on the pocket since tourists still need to take the plane and yadayada. The waves over at San Juan, La Union are also a lot more beginner-friendly.
You should visit the Ma-Cho Temple when you're in San Fernando City. It's just a mere 10 minutes away from San Juan and you can ride either a jeepney or a tricycle to reach the place. Like any other city in the country, there is a significant number of Chinese residents in San Fernando so it's not surprising that they have a Chinese temple around. The Mano Po movie also shot some of the scenes there. Entrance is free. Just be sure to not go around laughing or chatting boisterously.
For people who like to experience a little bit of Greek architecture, you can visit Thunderbird Resorts in Poro Point, San Fernando. It is approximately 10 minutes from the city proper. It's best to bring your own car because the guards will surely stop you and interrogate you when they see you walking around the area. However, you can still go there via jeepney or tricycle.
I recently visited the resort and well, it's fine. It's not bad but it's not that awesome either. Maybe it's just me :) You can spend a few days at the resort for at least P6,000/night. You can also just drop by and check out some of their restaurants.
La Union also has something to offer for those who love thrills. ThePugo Adventure, or more commonly referred to as PugAd, offers zipline, rapelling, and wall climbing activities.