Literacy programs for low level learners

I'm looking for a literacy program to use with our low level (high school) learners. A teacher recommended Words Their Way which seems like a really good foundation system for spelling and word knowledge. Has anyone used this? Also recommended to me by Pearson is a program by Fountas and Pinnel. This sounds more comprehensive in terms of reading development etc. Has anyone used this or anything other literacy development program that they find works really well?