While you don't have to get there right at opening and can sometimes walk right in, we like to get there before opening to ensure we are one of the first ones in only because seating can be problematic if you get there after it is already open. We think Trader Sam's is a fun place to meet other guests and really don't mind sitting anywhere as long as we can sit! We have noticed, however, that MANY people are uncomfortable sitting at a larger seating area with people they don't know there or would prefer sitting somewhere a bit more private (which is difficult in Trader Sam's). One time we ended up sitting in an area with a small shared table (we tend to spend at lot of time Trader Sam's and linger over drinks and appetizers), there were several very outgoing couples who came in and immediately sat across from us and we all had a great time talking together, but sometimes there were people who came in who were clearly not comfortable sitting directly across from people they don't know and they clearly did not want to talk. It became kind of a running joke with our server - some people would come in, see the empty chairs across from us, we would smile at them and gesture that they were welcome to sit, but they would turn around and walk out inside of sitting there! We are not scary looking people and we both showered that day (LOL!!) so clearly some people are just not comfortable in that kind of environment. We, however, have met a lot of really great people at Trader Sam's.
After all that my point is this - if you want to be able to choose where you are going to sit get there before it opens. If you don't care if you are seated with others who might want to chat it up, you can get there later.