Coming to Colorado is a great experience and I don't think one of us residents would discourage you, but you need to know a little bit about the airport. I travel in and out of it every other week, and, at times, it can be a real pain.
If you plan to use the bus system, do remember it is in the third lane and runs every half an hour. Don't expect the bus to stop unless you are almost in front of it. Several times I have run after it since it wouldn't stop for me. The buses don't run at night so don't come in too late. Buses also run to downtown Boulder, Broomfield, Littleton and suburbs to get you where you need to go.
The taxi ride to downtown is expensive, around $40. The airport is quite a ways from the downtown area; however, it doesn't look like that from the sky. Try, if possible, to split the fare.
If you must take a rental car, see if you can do it from downtown. I know it sounds like a pain, but you may save yourself $10-15 a day in taxes and such. The airport needs to be funded, and this is one area heavily taxed.
There are three concourses at the airport and a train to connect them to the main area. As I said before, I travel plenty through the airport and have been repeatedly stuck on the train. Watch your time at this airport - give yourself at least two hours extra. Hopefully, soon they will work out the bugs on the train problem :)
The food and concessions are just like any place else - expensive. Do consider the chain places for the run of the mill food but regular prices.
The absolute best part about DIA is the view. You can see the Rocky Mountains by looking to the west. They are big, beautiful, and, if you look hard enough, waving to you as you come for a visit.