My child is in Boulder school district, and I'll say that it's not a pretty sight for gifted kids. That's based on just one year's experience in the system for DD6 who skipped K. I don't know what your kids' ages are, but for K-5 there is one TAG focus school in the district - Lafayette Elementary (wish my child went there!). It has the most hours of a paid TAG Advisor at roughly 40/wk (the school population has doubled in 5 years to >600 since becoming a designated TAG focus school, and also the principal who really got that program established retired last year); by contrast my neighborhood school only has 10/wk from a less than inspiring TAG Advisor. I think the next highest might be High Peaks Elem. with about 30 hr/wk.
Peak to Peak Charter has a great reputation, but as you know is a lottery situation. There are 72 spots available at K, approx. 60 more spots open in 6th grade, and then another 20 spots open in 9th - pretty much if you don't get in those grades you won't get in at all. Aspen Creek in Broomfield started a pilot program last year where classes were cluster-grouped by ability which is probably helpful.
Macintosh Academy (private school K-8) has opened for this school year in Boulder near 65th St. and S. Boulder Rd. I'd like to visit the school soon myself. I know there were several families in Boulder who drove their kids 1.5 hours each way to take them to the Macintosh Academy in Littleton and they are thrilled to have it come to Boulder.
"Meager gifted services" just about covers it. Boulder is the land of perceived egalitarianism and Everybody is Special.