I have found 'Talking Thai' to be the best of all dictionaries. It's not a phrase book, per we, but you can find simple compounds like 'good morning' and 'goodnight' throughout. The strengths are native pronunciation for every single word, multiple 'context' of every word--such as how how may say 'puke' to your peers but 'vomit' to a doctor [not best example but works] and literary, dirty, obscene equivalents, a break down of every word by letter/syllable and words within words, a good primer on the alphabet, tones, syntax, usage, verbs, and the ability to search in English, via Thai sounds (not necessarily an easy option) or a more convenient one--reverse lookup Thai words.

Really helps to set your keyboard to Thai. I've never had a problem using it, find 99.9% of the words I'm looking for (and found many my wife says, "what did you say/where did you find that?", and it works completely offline (audio) included.

Think about $20USD. Best app I own for languages, and I have many for Thai, Spanish, German, Japanese, & Mandarin. Wish Rosetta Stone could update their Thai v1