Semi Formal - Please dress up as much as you are comfortable! (Preferably no jeans!) If you need ideas or inspiration check out this site: https://www.zola.com/expert-advice/what-to-wear-to-a-wedding
Late August in Colorado will still be pretty warm during the day (highs of 85), but it will cool down in the evening (lows of 60).
Yes, if you are comfortable bringing your kiddos they are welcome!
Please RSVP at least 30 days before the wedding. Formal invites will be send out closer to the wedding date, but if you RSPV sooner that is wonderful!