Denver is best during the summer, when the weather is ideal and the town is in party mode. The 16th street mall is a beautiful 12 or so block stretch of restaurants and shops with an upscale mall to top it off. Trolly's run every 45 seconds and provide free transport up and down the stretch of shops. Nearby is historic Larimer square, maintained in original architecture with live concerts and street shows throughout the weekends during the summer. The bar scene in this area of town is can't miss, with virtually every taste in mind. Everything from the Purple Martini for the upscale crowd to the laid back live jazz at the Chipoltipec. The Giggling Grizzly is a personal favorite. Clubs are first starting to improve in Denver, and the Bash is about the only one I would recommend, but Oasis isn't bad either. Cherry Creek is the high end part of town, and has a great mall and the best restaurants. Whether you're hanging out in Larimer Square, partying with the stuffy yuppies at Wash Park Grille, or riding the rollercoasters at Six Flags Great Adventure fun is everywhere in Denver.
Quick Tips:
Denver is best from June through August, and despite the heat, the dry climate makes for enjoyable weather. Street parties and concerts make downtown hopping. The bars go into high gear during the summer rush. The Six Flags is a great attraction, but the sports arenas are the can't miss part of Denver. Do whatever you can to get tickets to a concert at Red Rocks (natural rock amphitheater) as you will remember it for the rest of your life. If you hear a band at Red Rocks they will never sound as good anywhere else. The Denver Zoo is not worth the effort. Road trips are fantastic and a big plus to living in Denver. A few short trips include going to Boulder (45 minute drive to a beautiful town with great shops and restaurants), hiking St. Mary's Glacier (60 minute drive, 45 minute hike 900 feet, for almost any age in any condition - just know that there are no facilities if you know what I mean:), and a daytrip to Vail (2 hours there, 90 minutes back - gorgeous ski town with great shops and scenery). Whitewater rafting is a can't miss adventure trip.
Best Way To Get Around:
The bus and rail system is top notch and constantly improving, getting you anywhere for .25 or less.
Denver's unique infrastructure puts all the action in one centralized location. Denver is a sports town, with Coors field (Rockies), the new super arena the Pepsi Center (Nuggets and Avalanche) and Mile High Stadium (Broncos) all within relative walking distance to downtown. Taxis are not as easy to get when you want them as you would expect, but it is liveable. Denver is one of the cleanest cities in the states and crime is minimal, but the normal precautions should be taken.