Got some time to kill so here goes...
First, check out Clear Creek below Golden on Google Earth and pan your way downstream. You'll need to zoom out to get the street names and then zoom back in to see the Clear Creek. The aerial photos currently used were taken in the spring or early summer when there was a good flow in Clear Creek (I'd guess about 400 cfs at Golden), so you can see the rapids along the reach pretty well.
Anyone ever run the drop on Clear Creek upriver of I-70, just below where the trail crosses? It's about halfway between the Coors silos and I-70.
I think there are a lot of pretty shallow, manky drops on that stretch, which, combined with a culvert, make floating it pretty difficult. I don't usually bike up that far but it should all be scoutable from the bike path so you can check it out from CSM sometime and give us a report. If its runnable and the culvert shown in the aerial photo was only temporary for the Cabela's construction, it could be a good upstream add-on to the section described below.
I have goofed around on the Clear Creek town run a few times it has some fun 2-3 stuff.Shopping Cart Falls at Wadsworth has a good sized ramp that goes under a bridge and sometimes forms a decent sized hole + debris like pallets and shopping carts,it is hard to scout for junk at high flows due to shadows and glare off the water plus it is turbulent aeriated water,after that is a fast section with a concrete wall on one side sort of like a cliff,there is an unclean drop by some baseball fields....
There's a park at Youngfield/I-70 you could launch from and some potentially decent rapids just above Prospect Park. The bridge at Kipling may be too low to go under if the water's really up also. Then just below the 44th Ave bridge is a major horizon line and the glassy 8' or 10' drop. Believe it or not, but its actually fairly pretty down through that whole section of the Greenbelt - you'll notice that the sides of Clear Creek have lots of trees in the parkland along the creek. There's enough underbrush and buffer, and the creek's lower than the surrounding area so its not obvious you're floating through the 'burbs. You don't start getting into the urban blight until just above Wadsworth.
What you're calling "Shopping cart falls" at Wadsworth is what I referred to as "shallow, studded with nasty rocks for aereation, and has a big hole that may be a keeper and could surf & flip you for a nasty swim." You want to portage this in a raft because if the water's high enough to run the ramp into the hole without scraping the rocks embedded in concrete (maybe 600-800 cfs at Golden?), the hole at the bottom will be big enough to catch, surf and very possibly flip any raft small enough that you'd want to run the stretch with. If the water's low enough to run the hole, you'll have a nasty drag down the ramp on the aereation rocks and may spend the next weekend patching the floor instead of running the Ark or Poudre. You can see it on the upstream side of the Wadsworth bridge on the aerial photos - designed to be shallow and scratchy for aereation. There's an easy portage on the right side and you could still run the continuous set of rapids section along the wall just downstream of Wadsworth. There are actually boat landings above and below the Wadsworth bridge but they're too far above and below the hole to be much use if you're boating through.
I think the "unclean drop by some baseball fields" is the little rapid just below Marshall. I've run that in a raft and it didn't seem too bad at the level that day.
I haven't boated below Sheridan but have scouted down to the unrunnable seive/drop at Tennyson, (where there's also a possible takeout just above the bridge on the right by the bikepath). After that the neighborhood, water quality, and general atmosphere just gets worse, low-head dams become common as you get closer to the confluence with the south Platte and it isn't worth boating.
So to sum it up, with the exception of a mandatory portage at Wadsworth, the entire section from Youngfield to Tennyson could be a fun after work run for a paddle raft and a couple of kayaks, or especially a Mini-Me or a Shredder. Yeah, its nothin' spectacular and there are much better runs a couple of hours away, but hell, its right there in the backyard five minutes away for a lot of us...