There's Dazzle at 930 Lincoln. Major jazz names from time to time. http://www.dazzlejazz.com/calendar.htm
Not much going on that Sunday and Monday night....unfortunately.
Then there's El Chapultepec, on the corner of 19th and Market in LoDo, (Lower Downtown). El Chapultepec is a bizarre haven for modern day jazz musicians. Often times you can find the best players there after hours from an earlier performance at Dazzle. It's one of those strange but charming little places that brings in a diverse but devoted growd. Okay, it's a dive. Well worth swinging by on a jazz night. In the 50s and 60s, Ella, Sinatra, Ellington used to have their limos drop them off. Used to be a rough neighborhood but now it's about 2 or 3 blocks from Coors Field. It's fine. Once again, Sunday and Monday nights might be a problem.