As a VIP, I've gotten the worst table in a restaurant (Ruth's Chris in Bethesda) and one of the best (Indique Heights in Chevy Chase).

Some tips-
If you want a table for 6 but they will only accept for parties of 4 or less, make the reeservation online and then call to change. It almost always works.
If you want 7:30 and they only show 7:00 or 8:00 online, make the online reservation and call to change, again should almost always work.
When I call to change an online reservation, the change is then reflected on the website for most restaurants but not all.