ID for Tours etc

I'm not sure where you are getting your information, but it doesn't match my experience. Since you are posting in the "To The Boot" section, I'll try to focus on my experiences in Italy. You need your passport to check into your hotel, as the hotelier has to register you with the government. In the "olden days" they kept it overnight; now, they usually copy it and hand it back to you. You used to need a passport to cash traveler's checks at American Express. I haven't cashed a TC in years, and neither should you; use ATM's for cash. You have to show a passport when signing up to use an internet cafe (Italian law, to catch cyber-terrorists and cyber-stalkers). You also need a passport to buy an Italian SIM card for your mobile phone. For these purposes, a driver's license will not suffice. You often do need to leave ID when you are getting an audioguide at a museum; for this, a driver's license usually suffices. I have had to show my passport to get into the Jewish Museum in Munich, and I think I did this at some other Jewish sights with tight security. I don't remember having to do this at the synagogue in Rome. For French train tickets that you are printing at home, you have to show your passport along with the ticket (otherwise, dozens of people could use the same ticket). I don't think Italy requires this, but I haven't bought an online train ticket for Italy, so I don't know for sure. Often when you purchase tickets online to pick up later, you have to show the credit card you used to purchase it in order to pick it up. This is different from what you asked about, but I'm mentioning it just in case. That's all I can think of. Of course, if a specific ticket you have bought in advance says it requires a passport, that's different. Otherwise, don't sweat it.

Why are you not comfortable walking around with your passport? It is a small, light document which can easily be held in the inside pocket of a coat, for example. You could keep it in a secure money belt, but then it would not be readily available if you needed it. Of course it would be inconvenient if you lost it or it was stolen, but millions of people travel without that happening to them. You will need a passport when travelling out of your own country, and there is no evidence that leaving it in your hotel room is safer than taking it with you.

Legally, you're supposed to have your passport on you at all times. You can be asked at any time to produce it. Most places will accept a driver's license for audio guides and tour check in. For checking into your hotel they will take your passport to make a copy of it. They might hand it right back or it could take a few hours to get it back. This is normal. Just get a money belt and keep your passport with you. It's safer with you than anywhere else. Donna

We have carried our passports on us for 40 years with no problems. The recent earthquakes in Italy reminds me that I could need my passport unexpectedly at anytime. But to answer you question, the driver's license should be OK. We have used driver's license as a secondary id many times.

A tip my Italian instructor gave me was to take along an expired driver's license for those cases when you need to leave it to get an audioguide. It worked like a charm. She said she would NEVER trust the museum employees not to lose whatever ID you gave them.

To piggyback on Michael's post, even if you bring your current DL, it's alot cheaper and easier to replace it than your passport (when left as collateral for museum headsets, etc.). AND ditto what Frank said - With my moneybelt always on me, if my hotel burned, collapsed, or was similarly out-of-order (or any other building in the vicinity), I've got everything I need with me! I can go anywhere, buy clothes, eat, get on my flight home... I'm not comfortable leaving my passport in a hotel - safe (debatable!) or suitcase.