Travelocity will price the rate day by day with rate changes into it, so that if the rate drops you don't end up paying the higher rate for the entire stay.

Hilton sometimes averages the rate out to a different per day if there is a rate change, so make sure the total cost is better for you no matter which way you are going.

I've seen times where two nights, where the first is going for $209 and the second for $399 but both was $269 a night, which is acually a better deal then paying those two rates (those are real numbers, just checked them). So make sure you don't already have a good deal