Phrase books

You certainly can use your German and Italian also in Slovenia and Croatia. I only carry a small bilingual dictionary, (German/French and French/German.)

I brought Rick's phrase books with me to Germany, Italy, and Spain (separate vacations & phrase books). Each time, I was traveling with family, not a group tour. I have to say I didn't use them very much while actually on the trips, but I did use them. However, I found them very valuable for learning the languages before the trips. I like learning different languages and I think becoming familiar with the phrases and vocabulary is a good idea. I especially like Rick's phrase books because he emphasizes the practical phrases needed for traveling, especially the food items! I think the combo book sounds like a good idea for your trip.

Yes I have used them. What I like about RS versus others is that they include more useful, informal phrases. I think the combo is fine, as you may find you don't need it that often.

(edit) Kathy and I agree.

I agree with Kathy and Stan

I use them before the trips.

Look for books with two dictionaries in the back -- English to the other, and the other to English. That will help you with reading signs and such. The Rick Steves and Lonely Planet books both have these dual dictionaries. I give Lonely Planet the edge because it's smaller and fits better in my back pocket.

I might try Google translate... but realistically all you need to know for each country you are visiting :
Do you speak English?
Hello
Goodbye
Pardon me
Where's the toilette?