Depending on what countries you’re visiting will depend on the budget you need. If your tour is predominantly Eastern Europe then food in particular will be much cheaper than in Western Europe. In the major cities (Paris, Rome, Venice etc) eating in a cafe or bistro will cost between 20-30EUR for a meal and a drink. However, if you’re clever, you can cut this back by heading down the smaller streets and finding places where the locals eat. This will reduce costs to about 15-20EUR for a meal and drink.
I’ve always found that the most expensive meal of the day is lunch, not only in cost of the food but also in time. By the time you decide on a place to eat that doesn’t cost the earth and then get fed, you can spend almost 2hrs. In some places, this means eating and heading back on the bus. If possible, always take advantage of the packed lunch that the tour may provide. Fantastic for being able to eat on the run and then you just need to get a drink. Remember in Europe that unless you ask for tap water, you will be charged for water, so often it’s easier and cheaper to get a soft drink or juice.
Depending on what type of experience you want (party central or cultural) will also depend on your budget. Museums average betweek 8-15EUR for entry and if you want a souvenier afterwards, even a postcard will be 1-2EUR.
I would probably budget in EUR not USD as this is now the major currency in most places. Also, think about getting a TravelCard (through somewhere like Travelex) which means you can spend in EUR not your local currency. You can also then top up by BPAYing money onto it via the internet, which is great as you only need access to a computer and don’t have to worry about cashing travellers cheques or finding a Western Union if you’re having money sent.
Hope this helps.