I value mine hugely!
Living in the UK I don't want to pay to call the 800 number in the US. I like that she looks for the best rates for me - AAA/AARP and that she knows that I am a member of both organisations.
She fixes points and stays mis-postings and will let me know if there are any good bonuses for an upcoming stay which are hard to find now on the web site.
So, in summary, I book 99% of stay through my PL agent.
Oh, of course, she checks my lifetime points so I will know when I reach Diamond for life!