Small steps for better TCS conferences?
Keep prices down: you can get lovely hors d'oeuvres at a $750-per-seat hotel-hosted conference, it is true, but it tends to detract from the intellectual atmosphere you can get with a $100-per-seat university-hosted conference.  Also, you don't just get the people attending who deliver talks.  Allow students at the university to attend for free;
Space parallel sessions, so that people can really move between them;
But also encourage interaction between speakers and attendees at parallel sessions beforehand, so that parallel sessions are also autonomous communities.  This encourages interaction, and the sense that parallel sessions are moving the discussion in their subfield forward.  Some conferences (e.g., the German linguistics conference, DGfS) have taken this to the conclusion of having all parallel sessions be independent workshops.