Hmmmm... In the campaign I'm planning I have a similar situation. (Nature of The Beast. A loooooonnng project, mainly due to me having little time to work on it). Some of my thoughts on the matter:

1- What is the purpose of this base camp? From campaign planning perspective, but also from the players' perspective? Your campaign seem to focus on exploration, yet with intervals at the town, if I understand from the previous "Winter camp" thread? (I read it, but forgot to contribute). The thing is, if you're trying to make the base town very engaging, you're risking dividing the attention of the party.

I'll explain a bit- Before the current project, my gaming group conquered an enemy outpost, and with the help of their benefactor started converting it into a town and frontier outpost. But they were also expected to search the wastes for a secret enemy base. Now, this became a big problem- Two of the players got really invested in the town, making new organizations, ensuring it's safety, and so on (NOT talking about Kingmaker or mechanical aspects, nearly entirely roleplay!), while two really wanted to get out and start killing/ looting stuff!

This became a major point of dissatisfaction for the to sides, and some sessions were spent mostly in the town, while others were spent mostly at the outside, yet it was felt that at each point about half the group was also edging to get to the other part.

So, you'll need to think well and hard on the focus and time distribution of the campaign, and possibly set expectations with the group. Still, you might find the group/ certain players prefer to focus on exploration of the map and advneture sites, while others will focus on the town.

2- How "safe" is the town? Have you read a bit about the "West Marches" project? Quite an intriguing read. It also focuses on sandboxy exploration, but part of the design is that the base camp is totally safe, the adventurers can recuperate, rest, and not worry. No matter if they angered the gnoll tribe, killed the dragon's babies, or awoken a lich, once they are in town- they are safe.

In my campaign, one of the opposing factions specifically targets people form the town. (Usually for transformation into lycans), and if the PCs messes some of the wild factions, the town can easily be attacked. And that's saying nothing about schemes within the town itself. Yet... it got me thinking- say the players realize their town isn't that safe, or that NPCs they like/ get attached to, can be hurt? Will the players be ready to leave on long explorations? Or will they fortify in the town, seeking to defend it?

Or... if in the Diablo games, the town could come under attack, would the protagonist ever leave? Or stay to defend it?

I quite liked the "winter camp" idea, specifically for this, and I may burrow it for my campaign- Basically in "winter time", I expect (And wil ltalk with my players about it beforehand), the party may spend and interact in the town stuff, yet when the weather permits (Sunny season?), they are also expected to "seek out new life forms, and new civilizations... and to boldly go, where no man..." (You get the idea).

Not sure it will work though... Players can get really attached, and in a sandboxish game, it's kinda hard saying "But there is SOOOOO much to explore out there!"

3- Ok, abut making a town interesting. I got a few ideas:
a) Involvement:
In my campaign, the party will all get a significant primer on the town, and are expected to make most of the characters FROM the town, and having lived in it. Also, they will get a certain number of "contact points", which they can use to form contacts, either from the exisitng NPCS (When more influence or greater familiarity costs more contact points), or NPCs they create!
b) Their own touch:
Enable them to create small things about the place- An NPC or more, some building, some group, or such. Starting minor, but enabling them to become more major in the future possibly. All in cooperation with you.
c) Factions!
Players for some reason really like to get into factions/ groups, and gain status/ membership privliges and so on... D&D has some rules for this (Tough they are fairly lame I think), but you can easily make your own- Membership in an elite part of the guard, Membership in one of the temples, and so on...
d) Town conflicts!
Not threats from outside forces, but rather inside competition (And please, to make it interesting- DON'T make one side obviously better/ morally right)- Politics between guilds, nobles, a new religion setting up base, a conflict between some farmers and the land lord, and more.
e) Secrets!
Have you played Baldur's gate 2? (Shadows of Amn I think it was called?) The home base for most of the game was great at this- it had soooo many secrets to find in it! Secrets to places (A hidden celler, a hidden dungeon, a hidden... portal?), Secrets of people (A forbidden love, a shame well hidden, a chanegling/ doppleganger? The secret for Mary's SUPER DELICIOUS pie?), Secret History (This is not the first time this town stood here. And no, we didn't really conquer the goblins who've been here before...).
f) Interesting NPCs!
Forget the dwarven blacksmith. Instead making it a mute centaur blacksmith, who communicates via a blackboard, and clanging it's hammer percisely.
Or a trio of gnome shop keepers, helped by their erratic familiars?
Or a temple ran by the ghost of the old priest, which still seeks to lead his flock?
Or instead of the manor lord, the place is run by tow witch sisters, who's combined powers keep the dark forest at bay... for now?
g) Interesting themes!
The town isn't just "Generic village who happens to have all utilities for adventurers", but it has some hostory and special themes.
Is is situated at the side of a cliff, givign the town a height dimension?
Does it have a population of two races, some of which are mainly nocturnal, which makes the town change it's nature at night? (Give the phrase "the town that never sleep" a whole new meaning)
Does the town need to pay a monthly tribute to the 3 fey spirits which protect it (Or "protect" it?)
Is the town situated in a specific valley with unique accoustics, and has a special arena for musical performances?
Is the town cursed, for the sins of those who first conquered it? Do it's streets wail at night?
Was the town a former home for giant kin? DO majestic and huge buildings, with undeciperable writing, still exist?
h) One town, different sections!
Many interesting town have several sections/ parts/ districts- Market, slums, rich area, and so on (Usually with -2 creep places, such as necropolis, blasted magic zone and so on). The town need not be very big for this, and it also enables the players like some places more and some less, but still be in the town.
i) Change!
Have the town somewhat change as the game progress. From small changes (A wedding, a new business springs up, a funeral, a festivity) to big changes (Change of leadership, new fortifications/ major buildings, upscaling/ downscaling in size). It makes the place feel alive.

Anyway, just some ideas. Good luck!
(Also, I'm reading most of the threads in this specific forum... I think... Even if I barely got time to respond to some).