The ROMANIAN PHRASE BOOK & DICTIONARY from Berlitz is a standard entry in this line from the publisher. It features phrases for every situation a tourist could imagine themselves in, colour-coded for quick access, with both the Romanian text and a phonetic transcription for English speakers. At the end one can find a small dictionary, and a brief grammar. Romanian is an exceedingly easy language, and someone with previous knowledge of a Romance language could pick it up in two weeks, but if for whatever reason you'll be dependent on a phrase book during your time there, this is certainly the best phrase book around.
However, the phrase book does have some weaknesses. The information on Romanian culture often discusses matters limited to one particular region of this very diverse country without warning the reader that the words or concepts discussed aren't applicable for other parts of the country. The phonetic transcription is for speakers of British English, and were an American to unwittingly read from the transcription, being understood may be difficult. Editions of the book prior to the 2006 inexplicably continued to use the Communist-era orthography long after it was revised by a 1993 language reform. Finally, there are a few misprints, though I should think that these are not serious enough to deter communication.
Nonetheless, in spite of these quirks the Berlitz is the phrase book to get for Romanian--certainly avoid at all costs the Hippocrene ones.