This is the most valuable tool I found when I was planning a trip out there with my son 5 years ago. It shows you pretty much every public water way in the state, what species of fish is in it, and the regulations on different waters:
https://ndismaps.nrel.colostate.edu/index.html?app=FishingAtlas Our trip was for trout. He fly fished. I used spinners all week, and a few unscented soft plastics to drift. From your posts here, sounds like you mainly spin fish. Any rod you use here for smallmouth or trout will suffice out there. Many of the best creeks and rivers prohibit the use of live bait or plastics with scent in or on them.
Near Boulder, we fished Boulder Creek our first day there since it was close to where we stayed for the week. We didn't fish right in town, but you can. Boulder Canyon Road is about 15 miles long from Boulder up to Nederland, and there are several pull offs to stop and fish, which is what we did. We found lots of small wild browns in the 8-12” range and a few cut throats.
The Big Thompson River in Estes Park where it flows out of Estes Lake is easy fishing and we caught a lot of browns and rainbows there, about an hour from Boulder. Lots of pull offs as you drive it downstream along Highway 34 towards the town of Drake and lots of wild browns.
We did not fish any of the St. Vrain forks near Boulder, but you can read up on fishing those.
We also fished the Dream Stream section of the South Platte for two days, and spent time on the Colorado, Blue, and Middle Fork South Platte Rivers. Each of those is a good drive from Boulder, but the South Platte and Colorado (near Hot Sulphur Springs) are definitely worth the drive if you have a whole day to fish. The Blue is very technical water and micro midges, nymphs, and mysis shrimp flies are the way to go from my reading on it. We got skunked on it. We got our biggest fish on the South Platte, but did not get big numbers. The Colorado was good for numbers and quality of fish.