In the past you could reserve a seat with certain options like Greyhound Express and Priority boarding, but now all seats are first come - first serve.
This means that everybody lines up to board the bus and as passengers get on the bus they pick an empty seat and sit down. So you need to get to the Greyhound bus station that you will be leaving from early enough to get a good place in the boarding line.
Getting to the station 30 to 45 minutes before your bus is scheduled to leave will usually be early enough to ensure that you are near the front of the line. Being first in the boarding line allows you to get on the bus first and therefore gives you a better choice of seats.
So while the option to reserve a seat would be nice since you would know for certain that you have a seat, there is something to be said for being able to choose your seat. We've all gotten on a plane and groaned silently when we saw who was assigned to the seats next to us. At least on Greyhound you have options when it comes to your seating.
This doesn't mean that I agree with Greyhound's decision to suspend reserved seating.
I think they should follow the example of Megabus and at least have limited reserved seating on each bus. The reserved tickets would cost a little more but they would guarantee that you have a seat on a specific bus departing at a specific time.
This would ease the worry that many people have about their bus being overbooked and their having to wait and take a later bus. I'd say maybe like the first 6 rows of each bus should be reserved seating and all the passengers with those tickets get to board first and are guaranteed their seats. I personally would gladly pay an extra $10-15 for that peace of mind.
Perhaps one day Greyhound will bring back reserved seating. But until then the best we can do is get to the station early and hope there are some good seats left on the bus when we board.