I've never gone the agency route but I'm thinking of trying it.  In  the reviews I've read that interested me, a shower was involved that eventually lead to the bed.  My question is, is a half-hour visit enough time for all these activity or should one strive for the hour visit.

A 30 minute session will always be a more rushed type of session while a 60 minute or longer allows both more activity, or more time in each activity. If you're looking for a wham-bam see you later session 30 minutes will work. If not then you probably want a longer session.

Time depends on you.  I always prefer longer session so there's no rush.  But, that's more $.  The real question is how fast do you finish and how often do you want to finish?  If you can finish within 10-15 minutes you only need 30-45 minutes at most.  Toast and showers usually take about 5-8 minutes.  

And I definitely do not like rushing sex.  

A mutual shower beforehand once the woman arrives at my motel room is a great ice-breaker, I like to do it that way regardless of whether or not she or I have already showered.  

I like knowing her body is clean to my standards and I like her knowing that my body is clean to her standards.  Cleaning each other’s bodies is kinky, squeaky fun.  

It can also eat up most of a half hour, which is why I recommend more time than that for the session.  

One man’s opinion.