The biggest example I could think of for sticky areas would be in World of WarCraft. I used to play that game a lot, and I could easily think of certain places where it would be considered a sticky area. For example, a city could be considered a sticky area because being in a city gives you benefits.
Time to open up my trusty Photobucket account and pull all the pictures.
The most obvious benefit would be safety. For the most part, you are safe in a city. You could go AFK and you (probably) won't die. You could just derp around and be safe too.
But being in a city also unlocks gameplay features. For example you can join trade chat to talk to
I had a lot of stuff I could access.
In terms of other sticky areas, there's a bunch of them. There are a ton of areas in World of Warcraft where you would go because of other reasons. Areas where there's lots of daily quest givers, areas with a bunch of quick spawning mobs that drop important crafting materials, areas where rare mobs spawn, etc.
I used to farm for a lot of stuff.
I remember farming a ton of motes at the Elemental Plateau in Nagrand. I spent a lot of time there farming stuff so I could craft things and I would literally be there hours at a time, running around throwing damage over time spells on everything and watching them die, loot and repeat.
I also remember spending lots of time doing daily quests in certain areas like in Shadowmoon Valley for the Netherdrake mount, or to get enough reputation to get exalted in a specific faction just cause I wanted a fully lit green bar in my reputations page.
I remember going to that place every day for like a month to get enough rep for this mount.
In fact, now that I think of it, WoW actually has a lot of sticky areas. A lot of these areas aren't even like, short term sticky areas either. Many of them are long term, and stay sticky for long periods of times, ranging from a few days to a few months. There's so many that the player almost never runs out of areas to go to and do things in.
It keeps players busy. Keeps them playing. But most importantly of all, keeps them paying.