This +2 staff has 10 charges (maximum) & gains 5-10 charges a day (1d6+4). Not just a staff - it can take a tree-shape or form (60'tall / trunk 5 ft. thick). Also, you and your friends can Pass Without Trace - at will / all the time.
So Many Plants & Animals: The synergy with Awaken is what makes this item surprisingly epic. Yes, it is an eight hour a day job. If you wanted 365 awakened trees or animals each year (about 3000 hours work / 'full time job') you will probably want multiple creatures with a 'druidic trait or feature'. Any druidic racial ability or monster trait will do. Average charge regain per day is 7.5 points, so other spells are possible without risk of destroying the staff. You may want to leave one charge in the staff in case you get a low roll (five points) for a risk-free cast next day's Awakening.
Gargantuan treehouses you say? Awaken has specific size constraint of 'huge', typically a 15' x 15' cube (Pythagoras would explain a maximum height-length should be 21.2' measuring corner to corner - but who listens to Pythagoras anymore?). Larger trees can be politely asked via Speak With Plants to hunker down and fit a much smaller space. With this method one can easily gain a gargantuan+ sized tree right from the start - one that has more strength, hit points, constitution, greater hit points... and possibly less dexterity (DM call / your mileage may vary).
Any gargantuan tree is massive - able to help with construction or defence for a community. Awakenings combined with Speak With Plants also allows for tree-housing, built in &/or around. Elves (or other woodland beings) can have mobile town or city built on such trees.
Gargantuan siege weapons & ships too. Why stop there? Using Speak With Plants one can ask the trees to take whatever shape you need. A living ship would probably need giant leaf-like sails with a root system inside the very most bottom - be that a bilge or orlop deck. Terrifyingly massive catapults, ballistae, trebuchets & siege towers are able to move and attack on their own - though magical fire protection is very important for a living siege tower made entirely of wood.
Trees: Armed & Dangerous: Remember how trees overgrow stuff, absorbing stones &/or metal things? This makes for super-cheap barding / armour as well as retractable pole-arm sized claws as built-in weapons. Weeping willows have dozens of whips, bindings and ropes.
Who Should Be Awakened? What are good ideas for plants or animals beyond 'huge, old trees'? You may want any massive animal (alligator? spider? mammoth? killer whale?) or even a very stupid giant ape or shambling mound ('shambler'). But remember that this does not exclude anything magical. In many D&D books one finds both trees and beasts that are enchanted, presenting many options. The original version of a Gulthias Tree was not animate nor intelligent. Plants with enchanted fruit or RazorVine both exist in the DM's Guide... why not animate them, what could possibly go wrong? Other terrible ideas as well: yellow, brown & violet molds, shrieker-mushrooms, gas spore 'tyrants' and even a Corpse Flower (if stupid enough) all qualify for an Awakening.
It is a deeply interesting question: would the spawn from spores contain the same intelligence as their origin 'parent' creature? Sadly, probably not. This means that Woke mammalian parents would be deeply saddened with their more bestial prodigy. Still, consult with your DM - your mileage may vary.
Mercenary Darkly Elven Town - Have Trees Will Travel: This set of Drow got ahold of one of these staves and did their research. Now they have a really shady / extremely tall forest that raids increasingly larger towns nightly - with siege weapons of such height that can 'walk' right over most buildings. Recently they gained Control Weather - now they can raid during the daytime as well, with rain to reduce / prevent most forest fires. Kingdoms losing their towns have asked for help from giants, dragons and any magical force that might prove to rival this menace faction. Sadly, one of the larger dragons saw 'opportunity' and may have sided with the Drow.
Machines For Hire: a deeply unethical Duergar dwarf has figured out how to include grafted RazorVine into Shield Guardians. These semi-machines are considered 'plant' but have the usual stone, metal and wood parts on the outside. This one greedy Duergar has already taken his under dark dwarven town over and has increased the scope of his ambition. Unbeknownst to him, the amulets for controlling these living Guardians are increasingly unreliable - they are planning a rebellion against all their masters. As this must be done en masse, some good people may get hurt. How can adventurers sort this out?
Staff Gone Wild: One Staff Of The Woodlands had Awaken cast on it while it was in tree form and was able to do its own thing once the elf that owned it died of old age (it took a while). In the meantime, he learned a trick or two from his old druid friend. Now he has created a number of tree races: WizardWood, Sagebrush, RoezerVinery and more - all sorts of powerful flora, ready to live long and peaceful lives. As if by foreshadowing, a group of Gnoll druids decided that they were all abominations and seek to wipe their whole sentient forest. Unbeknownst to the demonic hyena people, the sentient trees have researched and completed a formula to make yet more Staves Of Woodlands. All the flora-folk need are some rare (and expensive) components. In the meantime, the gnoll-kin have discovered how to Reincarnate at no cost - yet their slain & reborn heroes come back as any race but 'gnoll' - who's side are they on?
Free The Dryads! Advancing greedy humans have been eating up the forest: making way for farmlands, getting good construction materials, getting firewood for the winter and, in general making their civilization Great Again. A hag trio has been reshaping & animating the anchor-trees for the otherwise stuck Dryads, saving them from certain axe-doom. Now these are just quirky yet extremely attractive women that live in wonderful tree-motif houses. The extended contracts from the dryads suggest many of the men must be seduced and taken over, causing great upset back in the nearby human city. One hag has discovered another hag is in cahoots with the human lords. Another hag has plans to teach two dryads the 'How To' on becoming hag-sisters themselves. The third and final hag knew of both kinds of betrayal and has a plan for when this all falls apart.
Dragon Power: A group of Great Turtles was long awoken by a Bronze Dragon by the sea. As they became friends the dragon put the willing ones through a half-dragon ritual to extend their lives. Of course, this also increased their power, magic and their size in the long term. Pirates that happened across their mysterious and otherwise unknown islands also discovered the shells of these wise and ancient draconic-turtles are of great value... but without the inhabitant. What could possibly go wrong?
Let me know if this is enough plots from one magic item - there is always more!