I've been playing a bit of WoW with some friends. WoW's world has a 24 hour day, so since we play in the evenings, I've been always seeing their world at sunset.
Part of a sense of place is how it changes over time. Days and nights, weather, seasons, the changing positions of the sun and moon. Growth, erosion, repairs and construction.
WoW's world has weather - rain, snow, sandstorms. Their time is tied to the real world; days last 24 hours, and a year is the same in either world. The moon is always full. The leaves never turn, and the snow never melts. There's an inn that's been being repaired for years, yet it never changes. There are annual holidays tied to the realworld calendar, and certain fish can be caught at different times of year. There's also a monthly fair that appears on the same date every month. Shadows are a strange mix; world objects have shadows that move in relation to the sun's position, while those of avatars and npcs are small circles directly underneath.
Time in SL moves at breakneck speed. Six days there to one in the real world. There's no seasons or weather or shadowing, although any particular area may have some if the current tenants wish it. If they're still there - neighborhoods change ownership and style in the blink of an eye. The wind changes force and direction. The moon is always full. There's a faint sense of year in the recurrence of Burning Life, The Relay for Life, and the track of the sun in the sky. You can also stop the movement of the sun in the sky in your own viewer, and even move the sun around in the sky. Island owners can stop the sun entirely - it is never noon in Midnight City.
For a quick visit or two, a place's cycles don't matter. A visitor won't notice them. The 2D/3D design, the usability flow, the sounds and colors are what they'll remember. But in the long term, those cycles are part of what defines a place. They're what we notice when we've come back after being away, they're part of how we mark time.