I don't think I will ever visit Columbine. I will not have the time to do it for the next 2-3 years and after that 20 years have gone since the massacre, so for me it doesn’t make sense, but I understand if other people want to. If I was in the Denver area I would probably rent a car and drive to Littleton.
Anyway, some boring and predictable answers:
1. Eric’s house
2. Dylan’s house (I would like to drive in the mountains there, beautiful landscape.)
3. Columbine High School
4. The strip mall where they worked at Blackjack Pizza
5. ? (Maybe the gas station where Eric bought the propane or the parking lot where they got busted braking in to the van)