almost every spot you go to will be predominantly on1 dancers. only on fridays at Images will you find a more even balance of on1 & on2. but since chicago is newer to on2, just about everyone who dances on2 dances on1.
buzz on wednesdays is great. there's a guestlist to get in free before 11. Buzz also does salsa on sunday nights--same guestlist for sundays will get you in for $5. there's another spot on Wednesdays that is more date-ish with live music each week from 7-11, no cover, funky ambiance & allegedly good food: carnivale. they tend to get really good quartets, or sometimes bigger combinations from the chicago salsa bands.
green dolphin on tuesdays is good--it's been a changing scene in hte last year or so. also a guestlist for that to get in for $5.
thursdays is best at excalibur. decent floor, good music, etc.
fridays at Images. other main option is to go to Rumba on fridays or saturdays, which will most likely be crowded and not a lot of the dancing crowd.
Let me know if you need/want the email addresses for those guestlists. I go out pretty often, so if you know when you'll be going, give me a PM & we can figure something out! Hope this is helpful.