In my experience so far, the most important factor in increasing industrial tech is placing a community college or university in your city. You can also accelerate the process of converting your industries to high tech by placing this near your industry. It will immediately boost their happiness (you will see green smiling faces pop up), and they will begin to develop very soon.
For example, let me give you a scenario from my play time last night. I had a decent size city going (50,000 pop), with demand through the roof for residential and industrial zoning. This city is currently the only one in the region, so there were no outside factors influencing my city education level, or any sims coming from other cities for jobs. I had a large industrial sector comprised completely of low tech dirty industry, even with a well funded grade and high school operating.
Having read the tool tip for the community college, I decided to plop it on the edge of where my industrial zones met my medium to low income housing zones, as the tooltip indicated it would help boost industry and be a place for mid income sims to receive college training.
The moment, and I mean literally the moment, that my community college staffed itself and opened its first classes... every factory within 4 blocks began upgrading itself to mid-tech industry. In fact, my income dipped about $4000 while all the factories upgraded at the same time.
So, in conclusion, if you want high-tech jobs, you need not only educated sims, but college educated sims, preferably university educated for the highest tech level.
Land value and happiness are separate concepts.
- Land value aka desirability encourage wealthier sims to move in.
- Happiness encourages density increases.
Residential happiness comes from shopping! Turn on the commercial dataview and make sure that shoppers can go from residential zones to commercial zones with available goods. (Goods resupply automatically at 6 am and 6 pm. Goods have nothing to do with freight).
Residentials without money or without nearby goods will instead go to parks to get happiness. This happiness is just as effective at growing density as shopping (ie. your buildings will grow). However, there are some downsides. Parks cost you money, while commercial buildings pay tax. Parks take up more space to get the equivalent capacity of commercial buildings. Parks also increase land value - so you may accidentally bring in wealthier Sims than you really want (wealthy buildings hold fewer people).
If you need more jobs, you might need denser industrial zones. Industrial happiness comes from making shipments of freight. Turn on the industrial view. If there is a large pile of shipments at any building, that industrial is in trouble. Make more commercial zones or trade buildings to receive those shipments. Once received, those shipments will automatically vanish at some point allowing more to be received.
Best Answer
Many structures in SimCity create a radius zone when you place them, this radiant is shown as either a circle around the structure or dots along the roads depending on the kind of structure you're placing. Parks and plazas create a radius zone, as do schools and police. Each of these structures provides an increase to land value for properties within that area.
The size of the area that is within the radius depends on the structure being placed, parks and plazas will affect a smaller area in comparison to police stations or fire stations. Placing multiple parks or plazas with their radius zones overlapping will stack, providing a greater increase in value.
Any specialisation you choose for your city will also have an affect on land value, for example specialising in Casinos will increase the value of commercial buildings in its vicinity.
Ensuring that you keep the streets of your city clean will provide you with a boost to land value, whilst letting them get backed up or not dealing with sewage will have a negative effect on your land value.
Abandoned buildings will also have a negative effect on the land value of nearby buildings, and have an increased chance of catching fire. Keeping abandoned buildings around over the long term will drive down land value for the surrounding area and it is usually recommended that once the building goes 'dark'. It is better to bulldoze that building to prevent it from causing damage to the value of the surrounding buildings.