I'm not aware of a good list, but here's what I use:
Adams:
Thoroidin is your best bet if you have an 800 only scanner for the Adams metro area stuff.
If you're in western Adams Co and have the capability, the 700 MHz simulcast site should also be used. As with all simulcast sites, you can't count on it working well if you're outside the intended coverage area.
The Hoyt site covers the rural areas of eastern Adams.
Arapahoe:
The Chevron site works real well for most Arapahoe metro area stuff.
The DTB site in Glendale is a good one for that area.
Smoky Hill and Silver Heights cover C-470 & E-470 well.
I wouldn't mess with the Arapahoe Admin site unless you're fairly close to Belleview and S. Santa Fe.
If you're going east on I-70, the ZAP site near Bennett and the Deer Trail site are the ones to use in Arapahoe Co.
Broomfield:
Thoroidin is your best bet, and maybe the 700 MHz Adams simulcast, as well.
Douglas:
I like Silver Heights for a lot of Douglas Co stuff. It covers the Castle Rock area real well.
Chevron and Smoky Hill should also be useful in the Parker area.
The Franktown site should be good around Franktown...
And West Creek is good for southern Douglas Co.
Jeffco:
Lookout Mtn is the main one to use for all metro area Jeffco stuff. If you're just in the metro area, I'd just use this one.
Thoridin is useful if you're up in the northern Jeffco mountains, like Coal Creek Canyon.
Silver Heights is about the only one you can hear at certian parts along C-470 thru Jeffco (like around Bandimere Speedway).
Riley Peak is useful if you go up into the hills on US-285.
Squaw Mountain is useful if you're around or west of Evergreen on I-70.
Weld:
The Bald North site west of Loveland is a good wide area coverage site for Weld.
Of course, use the Ft. Lupton site if you're in or near Ft. Lupton. Same with the two Greeley sites.
The Point of Rocks site can be heard well along I-76 around Wiggins.
If you're up in the northern boonies of Weld, the Grover and New Raymer sites would be useful.