"We are going to be asking people" is an incomplete sentence. You could say, for example : "We're going to be asking people about the weather during the festival." It implies that you'll be involved in the process of asking the people during that time frame (the festival). In the sentence "We're going to ask people about the weather during the festival", you state the action that you intend to pursue, but it does not imply that you pursue actively the process of asking people. Hope that helps.