Hotel
One of the most historic hotels in downtown Boulder, this hotel is near all the action of 6th St.
Hotel
By far the nicest hotel in Boulder, this hotel is centrally located and luxurious.
Hotel
House Or Rental
Consider renting an Airbnb anywhere in the Boulder, Longmont, Lyons or Niwot area.
Train
You are free to rent a car, but if you would like to save the expense, there is a very cheap and reliable shuttle running from DIA to Boulder every hour: https://greenrideboulder.com/
Travel Note
I understand that a lot of families may want to make a vacation out of your trip to Colorado and I recommend doing it the week after the wedding. I have found in the past that traveling out into the mountains the week of July 4th (the weekend before the wedding) is horrible traffic. If you do choose to take advantage of the July 4th holiday, book your accommodations or camp spot ahead of time.