For most shows best position for you, whatever that means, will be about the length of time you have been in the show or the size of your stand. So rebook on site. It doesn't just help the organiser - it helps you, confirms where you are in the show. The second thing I would say is, look at ways in which you can cluster with companies who are meaningful to you, your partners, your media partners, your business partners. But then, create more scale, more interest for yourself by being near people who are like you. Look for the number of sides you can have open. Two sides are clearly better than one side open on a stand. Think about those kind of positional tweaks. The other thing to do is engage with the organiser. There is simply not enough dialogue between exhibition organiser and exhibitor on most shows. The more you talk to the organiser, the more you are going to be able to leverage your relationship to get what you want, whether that is better stand position, whether that is seminar speaking slots, whether that is a better deal on sponsorship opportunities. There has been a tendency in the past for exhibitions to be space sold and then everyone goes their separate ways until the day of the show. I'd advocate a completely different approach. Understand everything your organiser is trying to do. Question them. Not because you are trying to catch them out but because you are trying to understand their objectives for the show so that you as an exhibitor can interact with their objectives. This should be about media partnership.
