Doesn't look like any big conventions are in town. Maybe just because it's a weekend? I'm guessing rates might come down.
As long as you book directly with a casino property (not Priceline or some other 3rd party reseller) you should be able to change your reservation....but go ahead and reserve something if it will give you peace of mind. April weather conditions are normally very inviting (warm enough for pools but not 100+) so that definitely drives up room prices.
NAB (National Assoc. of Broadcasters) happening in April. One of the larger conventions, approx 100K attendees. Hard to say if the rates will come down or not, but I'd book something that you can cancel and rebook if the prices do come down.