In looking at summer concerts this year, I have noticed that it seems like there are 2 tiers of summer concerts and venues. For example, artists like Green Day, Dave Matthews Band, John Mayer, and Maroon 5 seem to be playing at the same 20 or so venues, while artists like O.A.R., Sublime, Counting Crows and Goo Goo Dolls are playing at different venues. Does anyone know if this has to do with most of the big amphitheaters (the ones that Green Day, DMB, and others are playing at) being owned by Live Nation, and most big artists signed to Live Nation? Any comments on this would be great!