Some places frequently mentioned here are Barr Lake which might be a bit of a reach for the north metro area.
One place I know for sure are the ponds at 88th and Colorado. There is a gal by the name of Koni (if you search for her name you will find the posts) that caught a couple of 11 pounders out of those ponds last year. I have caught walleyes up there too. They just opened last year. If you are willing to walk a little you can leave the crowds behind. They are old gravel pits and drop into 20 feet of water fairly quickly and seem to be uniform. Koni caught her cats out of the northern most one (it has two fishing piers). If possible I would pick the side the wind is blowing into.
I also seem to remember someone posting that Lake Arbor has cats in it too with them actually catching some.
The division of wildlife puts out a fishing close to home publication for $5 available at most sporting goods. It lists all the metro areas with locations of ponds and lakes with species stocked.