The Arnold Classic has become the biggest pro event in the U.S. The Olympia has slipped quite a bit, & I don't think it will recover. The Arnold is the only event left in the U.S. where you will see a large number of pros covering the booths for their sponsors.
Tickets for the men's pro event are sold out well in advance, but you can look at
this page for more info.
Many of the events are free with an Expo admission ($10/day). The Arnold is known for its Expo. Don't buy Expo tickets in advance. You can get them there without surcharges.
New this year will be an
Arnold Amateur Classic.
Hotels will be a problem this late. Even in neighboring towns, rooms are booked up the prior year. You can try
this list,
this site, or the "Contact Us" link on the same page. Downtown is closest.