Hi @TERRI5 , you didn't mention time of year...summer or winter - HUGE diff for Colorado.
Assuming - not - winter, most trails in Colorado are very well maintained, and where needed, switchbacks! (mostly)
Intermediate level is usually applied in relationship to altitude, e.g. the trails become 'harder' the higher you go because of difficulty breathing, and consequently, weakening your whole body.
Although day hiking footwear is important, many will offer that allowing time to acclimatize, especially any hikes over 10,000', is equally important.
You didn't mention where you're coming from, so there's the possibility you will have an easier time of it (acclimatization) than those traveling from sea level.
Many folks visiting Rocky Mountain National Park, can day hike from any popular trail head up to about 11,000' and find themselves with high altitude sickness symptoms on the way down.
Anyway....back to the question, IMO almost any lightweight shoe/trail runner which fits well and is comfortable, will do fine, for day hiking.
Please take and post some pix!