I've been building and testing a number of different antenna styles on ESP-07's.
One very simple and successful antenna I've tried so far has been making a tin can wave-guide, also known as a "Cantenna". I've build two and set one up as an AP with a TCP server that just loops back.
Today I set one up pointing at Mt Taylor out a window, and walked up Mt Taylor with the other and laptop. Results were pretty awesome. This is a 2km distance with direct line of sight. From the top of the hill I had a -74db RSSI to the AP ESP, which has some more distance in it.
Perhaps we should look at mounting some weather stations on hills around Canberra and feed weather underground (with appropriate permissions of course.)