You can go by these ways: ( through border only )

1/ Flight to Ha Noi.
Flight to Ha Noi, and depart to Laos through Cau Treo border ( located Nghe An province ), on this way, you can travel Laos ( Vienchan, Luongprbang ), Thai ( Udonthani... ) or flight Ha Noi to Da Nang, or Hue, then go Lao by border.

2/ Flight to Ho Chi Minh.
Flight to Ho chi minh, depart to Laos through Lao Bao Border ( Quang Tri province ), or flight or train or bus to Da Nang or Hue.