Tip #1: The light rail (train) is a great way to travel between the airport and Union Station in downtown Denver, and a good excuse to visit Union Station which is a cool place. The train station at DIA is accessed from level 5 adjacent to the Westin hotel (follow signs for "Trains to City" or "Transit Center" and there are kiosks, by the trains, for purchasing your ticket.
Tip #2: DIA is 23 miles from downtown Denver, almost 30 from Lakewood. Lyfts and Ubers run anywhere from $45-$60 one way, so if you want to save some money see Tip #1!
Tip #3: Denver is, quite literally, a mile high (5280 feet above sea level) and dry. For those coming from lower altitudes, we urge you to drink more water than you normally do.
Tip #4: Upon departure, please note that DIA has gotten ridiculously busy, and when they say to arrive two hours prior to your flight they mean it. Even Colleen, who is notorious for skating in just in time for boarding, now heeds this advice!
There are many good hotels and Airbnbs in the area. Here are two hotels we really like: