I'm also self-studying. I have a third suggestion. It's called First Latin Lessons
by Harry Fletcher Scott. It was published so long ago that now it's in the public domain, and can be downloaded from http://www.archive.org/details/firstlatinlesso00scotgoog
(specifically the PDF version is at http://www.archive.org/download/firstlatinlesso00scotgoog/firstlatinlesso00scotgoog.pdf
The good thing is that even if you find you don't like it later, it's free so no money lost. Here's why I like it:
- There are many small lessons (64 to be precise). They're small in the sense that the reading passage is only a few paragraphs.
- Grammar points are explained and new words are translated into English
- There isn't a lot of new vocabulary every lesson
- Later in the book are longer stories to read
- There are even latin songs included!
I bought Wheelock's Latin book a while back but found it tough-going. Wheelock believed it was a good idea to get you reading actual classic prose, but of course it was too difficult for a beginner to read, so he simplified the sentences. The only problem is there's no context for the sentences (they're not part of a story) and he had to add in some complex vocab that's just used once in that sentence. The result is a bit of a mess. At least with "First Latin Lessons" you're getting simple text passages that only use the vocab covered so far. Plus the passages are a cohesive whole and once sentence builds on the previous.
I've also tried Lingua Latina per se illustrata, it's very well put together, but perhaps I rushed too fast and felt overwhelmed with the density of new words. I'll go back to it later as it's great for vocab.
Oh, and I should mention that there's a follow-on book to First Latin Lessons called A Junior Latin Reader
which has 35 more lessons.