The Alta ski area has really good lift infrastructure and 891 hectares of ski area. Alta is well-known for its extremely challenging terrain, but there is also a good play ground for beginners and intermediates.
Alta ski resort is inter-connected with Snowbird via the lifts and slopes (via the saddle off the Sugarloaf chairlift) or a free bus. If you pay the extra money for a combined Alta/Snowbird lift ticket you get even more terrain. Together the resorts provide 26 lifts and 1,902 hectares (4,700 acres) of terrain, making it one of the largest ski areas in the US.