|I know that Squaw and Heavenly get all the press but mostly because of their steeps.
Both Squaw and Heavenly have more beginner and intermediate terrain than diamond and "extreme" skiing. Cliffs and chutes make great pictures and press, but the people who spend money and are essential for ski area survival are more like you. These ski areas can meet your needs with lots of terrain, and most visitors to these areas never set foot in a couloir or huck off a cliff. These areas are well known because they are the largest in Tahoe for Vertical, area and runs, and they meet the needs of a wide variety of skiers.
Heavenly is one of the largest resorts in the area and has one of the largest verticals in Tahoe, but it is difficult to ski it top to bottom due to traverses and the need to connect multiple lifts to reach the summit. This is an advantage because it discourages snowboarders. Chances are you can spend days exploring the blue and green terrain off Sky Express, Canyons, Powder Bowl in California and Comet, Dipper, Galaxy, Tammerack and Stage Coach in Nv. Trails are well marked and you will not accidently stray onto diamond terrain.
Squaw Valley has miles of intermediate terrain and features more open skiing rather than trails. Squaw is rightfully well known for extreme terrain and celebrity skiers, but the majority of the area is enjoyable by mere mortals.
Sierra at Tahoe offers 50% blue terrain including nearly the entire West Bowl area and the 2-1/2 mile long (green) Sugar and Spice trail. Sierra is located only 20 miles from Kirkwood near Echo Summit and gets more snow than most areas in the Tahoe basin. SAT is a smaller area with over 2200 feet vertical that you can quickly become familiar and comfortable with. SAT sells lots of season passes that are good at both Sierra and Northstar. So, lots of locals ski here. Weekdays are all to yourself, but weekends and holidays can feel crowded.
NorthStar is a huge area with most advanced terrain confined to Backside and Lookout. Its a big area that could take you several days to cover just the blue and green terrain. Both Sierra and Northstar are owned by the same company so you can get a package deal to ski both, but the distance between them is considerable. Very family oriented atmosphere.
There are something like 15 ski areas here. You would have a hard time NOT finding something you like at any one of them, including the unknown areas like Homewood, Donner and Boreal or mid-size Diamond Peak, Mt Rose and the destinations of Sugar Bowl, Alpine Meadows, Kirkwood. Here is a link with a list of areas and some basic stats. http://www.virtualtahoe.com/SkiTahoe/SkiAreas.html
In the 15 years I have lived here, I am yet to ski all these areas. Shame on me.