Personally, I find it rather pointless to ask people's average speed around here. Everyone but me seemingly rides 22MPH up a 10% grade into a headwind sitting down spinning on the big chainring...

Instead of asking what people average, as it is different for everyone, figure out what you need to average for your distance and duration, and ask yourself if it is reasonable. If you normally ride fast, it shouldn't be much of an issue (ok, maybe a mental issue) to ride slower. For the first tour I've planned, that I leave for next week, I've planned out over a week's time a mileage I know I can ride in three to four hours for each day, and have given myself all day to do it to account for anything I haven't considered or to stop for things that are interesting. Speed is the last thing on my mind in anything but a timed event.