Be prepared to pay big $

Hotel in Europe is totally different from US. Cheap hotel could mean it does not have its own bathroom. So you need to be aware. Hotel in London in summer is very very expensive. Motel style room costing $70 in San Francisco can ask $300 in London!

My suggestion is that you check out lower end US based name brand, such as Holiday Inn Express. They operate more like US motel and have good quality. You also need to consider where the hotel is. Make sure it is within walking distance of underground and it is in a safe area. Very important!